chore(blooms): Replace extracting line filters with extracting label filters

[chaudum]

What this PR does / why we need it:

Replace the logic for extracting line filters with extracting label filters on the bloom gateway client, because otherwise the bloom gateway server would receive requests with no label matchers.

Checklist

• Reviewed the CONTRIBUTING.md guide (required)
• Documentation added
• Tests updated
• Title matches the required conventional commits format, see here
  • Note that Promtail is considered to be feature complete, and future development for logs collection will be in Grafana Alloy. As such, feat PRs are unlikely to be accepted unless a case can be made for the feature actually being a bug fix to existing behavior.
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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

[emadolsky]

Hi! This doesn't seem right. Or at least the document should be updated that line filters are not being considered for bloom filtering:

loki/docs/sources/operations/query-acceleration-blooms.md

Lines 215 to 216 in 5bffc10

	- The filtering expression contains at least as many characters as the n-gram length used to build the blooms.
	- For example, if the n-grams length is 5, the filter `|= "foo"` will not take advantage of blooms but `|= "foobar"` would.

Or maybe I'm getting this wrong.