Fix for SMEditableGridTest.testDragFillReadOnlyColumn (#2936)

#### Rationale
The beginDrag method for the UI component has a 150 ms timer to
distinguish between a drag and a click. I've added a 200 ms wait to the
drag action in the test to account for this.

#### Related Pull Requests
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#### Changes
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this comment) -->

Author: DariaBod

src/org/labkey/test/components/ui/grids/EditableGrid.java

@@ -1040,6 +1040,7 @@ private void dragToCell(WebElement elementToDrag, WebElement destinationCell)
                 // WebDriver doesn't calculate correct location to click the cell selection handle
                 .moveToElement(elementToDrag, 0, 7)
                 .clickAndHold()
+                .pause(Duration.ofMillis(200))
                 .moveToElement(destinationCell)
                 // Extra wiggle to get it to stick
                 .moveByOffset(0, -size.getHeight())