fix: lambda-promtail, update s3 filename regex to allow finding of log files from AWS GovCloud regions

[Overflow0xFFFF]

What this PR does / why we need it:

A broken regex prevents AWS GovCloud regions from properly being supported with Lambda Promtail. The regex matches only on regions with three parts in their filenames (e.g., us-east-1), and the GovCloud regions have four parts (e.g., us-gov-east-1).

Which issue(s) this PR fixes:

No issue found.

Special notes for your reviewer:

The fix is to add an additional, non-greedy, non-capturing group to match on the fourth parth. Initially, I attempted to use (?:[\w-]+) for its simplicity and to match on the region-parsing logic we already have. However, this breaks the tests for vpcflowlogs because of the greediness of the + operator. As such, I opted to write something more verbose, but non-greedy.

Tests have been added to prevent future breakages, as this tends to be an edge case.

Checklist

• Reviewed the CONTRIBUTING.md guide (required)
• Documentation added
• Tests updated
• Title matches the required conventional commits format, see here
• Changes that require user attention or interaction to upgrade are documented in docs/sources/setup/upgrade/_index.md
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• If the change is deprecating or removing a configuration option, update the deprecated-config.yaml and deleted-config.yaml files respectively in the tools/deprecated-config-checker directory. Example PR

[CLAassistant]

All committers have signed the CLA.

[cstyan]

👍 thanks @Overflow0xFFFF