refactor(backend): Relocate User Login info from User table to AuthProvider table

[Neilk1021]

What changes were proposed in this PR?

As discussed in #6716 we'd like to split authentication handling into its own table auth_providers. For future support of multiple sources of authentication (e.g. github, IEEE accounts, etc.). This PR migrate the Schema from the image on the left to the one on the right.

This PR:

1. Creates a new auth_providers table in texera_ddl.
2. Providers a migration script 29.sql to migrate old account data to the new schema.
3. Refactors backend to match new schema.
4. Refactors portions of GoogleAuthService to a generic ExternalAuthProvisioner to be used in future PRs adding new external logins.

Any related issues, documentation, discussions?

Closes #7048

How was this PR tested?

Compiled and ran all tests as well as deployed locally to verify functionality.

Was this PR authored or co-authored using generative AI tooling?

Co-authored with Claude Opus 4.8

[github-actions]

Automated Reviewer Suggestions

Based on the git blame history of the changed files, we recommend the following reviewers:

• Contributors with relevant context: @Yicong-Huang, @Ma77Ball, @mengw15
  You can notify them by mentioning @Yicong-Huang, @Ma77Ball, @mengw15 in a comment.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 79.78%. Comparing base (421e660) to head (0f5e89d).

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #7055      +/-   ##
============================================
+ Coverage     79.57%   79.78%   +0.21%     
- Complexity     3832     3839       +7     
============================================
  Files          1159     1159              
  Lines         46122    46041      -81     
  Branches       5127     5114      -13     
============================================
+ Hits          36700    36734      +34     
+ Misses         7790     7673     -117     
- Partials       1632     1634       +2     

Flag	Coverage Δ		*Carryforward flag
access-control-service	70.00% <ø> (ø)
agent-service	77.42% <ø> (ø)		Carriedforward from 421e660
amber	73.38% <ø> (+0.31%)	⬆️	Carriedforward from 421e660
computing-unit-managing-service	31.57% <100.00%> (+11.08%)	⬆️
config-service	66.66% <ø> (ø)
file-service	67.21% <ø> (ø)
frontend	83.05% <ø> (ø)		Carriedforward from 421e660
notebook-migration-service	78.94% <ø> (ø)
pyamber	97.36% <ø> (ø)		Carriedforward from 421e660
workflow-compiling-service	26.31% <ø> (ø)

*This pull request uses carry forward flags. Click here to find out more.

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[github-actions]

⚠️ Benchmark changes need a look

🟢 6 better · 🔴 7 worse · ⚪ 2 noise (<±5%) · 0 without baseline

CI benchmark results are noisy; treat <±5% as noise unless repeated.

Dashboard · Run

	config	throughput	MB/s	latency	max Δ latest / 7d
🔴	bs=10 sw=10 sl=64	435	0.266	22,209/28,541/28,541 us	🔴 +86.2% / 🔴 +80.8%
🔴	bs=100 sw=10 sl=64	934	0.57	103,461/149,816/149,816 us	🔴 +28.1% / 🔴 +35.8%
🟢	bs=1000 sw=10 sl=64	1,100	0.671	903,964/1,021,984/1,021,984 us	🟢 +18.1% / 🟢 -10.4%

Baseline details

Latest main ebfd1db from 2026-07-30T14:07:03.708Z

config	metric	PR	latest main	7d avg	Δ latest	Δ 7d
bs=10 sw=10 sl=64	throughput	435 tuples/sec	732.84 tuples/sec	771.62 tuples/sec	-40.6%	-43.6%
bs=10 sw=10 sl=64	MB/s	0.266 MB/s	0.447 MB/s	0.471 MB/s	-40.5%	-43.5%
bs=10 sw=10 sl=64	p50	22,209 us	13,439 us	12,626 us	+65.3%	+75.9%
bs=10 sw=10 sl=64	p95	28,541 us	15,329 us	15,786 us	+86.2%	+80.8%
bs=10 sw=10 sl=64	p99	28,541 us	19,526 us	19,344 us	+46.2%	+47.5%
bs=100 sw=10 sl=64	throughput	934 tuples/sec	897.82 tuples/sec	971.56 tuples/sec	+4.0%	-3.9%
bs=100 sw=10 sl=64	MB/s	0.57 MB/s	0.548 MB/s	0.593 MB/s	+4.0%	-3.9%
bs=100 sw=10 sl=64	p50	103,461 us	110,657 us	103,463 us	-6.5%	-0.0%
bs=100 sw=10 sl=64	p95	149,816 us	116,972 us	110,296 us	+28.1%	+35.8%
bs=100 sw=10 sl=64	p99	149,816 us	132,496 us	118,690 us	+13.1%	+26.2%
bs=1000 sw=10 sl=64	throughput	1,100 tuples/sec	931.46 tuples/sec	1,001 tuples/sec	+18.1%	+9.9%
bs=1000 sw=10 sl=64	MB/s	0.671 MB/s	0.569 MB/s	0.611 MB/s	+18.0%	+9.8%
bs=1000 sw=10 sl=64	p50	903,964 us	1,071,100 us	1,008,988 us	-15.6%	-10.4%
bs=1000 sw=10 sl=64	p95	1,021,984 us	1,109,394 us	1,055,260 us	-7.9%	-3.2%
bs=1000 sw=10 sl=64	p99	1,021,984 us	1,125,922 us	1,074,689 us	-9.2%	-4.9%

Raw CSV

config_idx,batch_size,schema_width,string_len,num_batches,total_ms,total_tuples,total_bytes,tuples_per_sec,mb_per_sec,lat_p50_us,lat_p95_us,lat_p99_us
0,10,10,64,20,459.77,200,128000,435,0.266,22208.97,28541.10,28541.10
1,100,10,64,20,2141.91,2000,1280000,934,0.570,103461.27,149816.29,149816.29
2,1000,10,64,20,18181.88,20000,12800000,1100,0.671,903963.57,1021984.04,1021984.04

[Neilk1021]

@Yicong-Huang can you please look this over when you get the chance, thanks!