Add service.idling: 1 to all ftests + decrease size of ftest for gcs

Closes https://github.com/elastic/connectors/issues/2638

Functional tests became a bit slower after change in https://github.com/elastic/connectors/commit/b8b66aa31dec2d48396c7e79e604e9290695c82f#diff-5f4b320c98a5619e1197864adbca34517cf6ce4aafdb3d17ca5079dc859998a1: now cron does not respect seconds at all (which is impossible to change in Kibana anyway), so tests started to run a bit slower - full sync is scheduled 30/60 seconds later.

This PR slightly speeds up functional tests by making service.idling: 1 making service poll for jobs and try to schedule jobs every second.

Additionally this PR decreases the GCS functional test payload by around 10% so that it would always pass. Now test takes around 500-550 seconds and with scheduling taking up to 90 seconds it could exceed the threshold of 600 seconds that ftests has to run the first sync.

One small change is just standartisation of all ftest config.yml files: deleting unnecessary lines.

Checklists

Pre-Review Checklist

[x] this PR does NOT contain credentials of any kind, such as API keys or username/passwords (double check config.yml.example)
[x] this PR has a meaningful title
[x] this PR links to all relevant github issues that it fixes or partially addresses
[x] if there is no GH issue, please create it. Each PR should have a link to an issue
[x] this PR has a thorough description
[x] Covered the changes with automated tests
[x] Tested the changes locally
[x] Added a label for each target release version (example: v7.13.2, v7.14.0, v8.0.0)

Status	Branch	Result
❌	8.13	Commit could not be cherrypicked due to conflicts
✅	8.14	https://github.com/elastic/connectors/pull/2654

elastic / connectors