fix: miscellaneous snippet gen fixes

[dwsupplee]

While going through the influx of new PRs generated by snippet gen I discovered a handful of issues which this PR addresses.

Each commit addresses a separate issue, if preferred I can open multiple PRs - but I thought it would be nice to have the test updates all in one place.

Here are the learnings/fixes:

1. Fields with a format method aren't only applied at the base request level, they can be found in nested messages as well. Adjusted for this.
2. Updated inline var block on getResultscalls in LRO samples to annotate the correct item.
3. Prevent calling serializeToJsonString on primitives.

I also temporarily disabled the inline var block for paginated samples on REST only clients. When the resource type is a map the MethodDetailsclass is having trouble determining the correct type to display. Seems like a wider issue that I plan to address separately.

[bshaffer]

This looks great! One small request