curl examples, misc syntax

[jstirnaman]

@copilot file your unresolved comments in a single separate issue

I don’t have issue-creation permissions with the tools available in this environment. Please file one issue with these unresolved review items:

• content/shared/influxdb3-get-started/query.md:323-324: split curl command missing line-continuation \.
• content/shared/influxdb3-sample-data/sample-data.md:97 (and similar URLs in file): curl URL with & query params should be quoted.
• content/shared/influxdb3-sample-data/sample-data-dist.md:100: curl URL with & query params should be quoted.

Originally posted by @copilot-swe-agent in #7503 (comment)