Improve logging pattern schema validation

[TinaHeiligers]

Summary

This makes pattern schema validation stricter by avoiding unrestricted matching, enforces realistic timezone constraints, and sets an upper bound to the date format string.

Characteristic	Before	After
Optional Groups	Capturing groups for optional sections.	Non-capturing groups for optional sections.
Timezone Validation	Allows any characters except }.	Restricts to A-Za-z/_+-.
ReDoS Prevention	Broad matching with [^}].	Constrained matching for timezone.
Clarity	More complex and verbose.	Cleaner, more restrictive, and simpler.
Performance	Captures unnecessary groups.	Limits captures to needed named groups.

[elasticmachine]

💚 Build Succeeded

• Buildkite Build
• Commit: ebf8161

Metrics [docs]

Page load bundle

Size of the bundles that are downloaded on every page load. Target size is below 100kb

id	before	after	diff
core	454.0KB	454.1KB	+16.0B