fix: RemoveYAMLComments considering hashtag within strings as comment

[varas]

RemoveYAMLComments considering hashtag within strings as comment.

Golang does not support negative lookaheads golang/go#18868
There's an alternative library https://github.com/dlclark/regexp2 but here we are sticking to stdlib.
For this reason it's required:

• several regexes
• several capture groups that will be discarded

We are not trimming whitespaces for simplicity.

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This also logs the (previously shadowed) original error on config error.

[coveralls]

Pull Request Test Coverage Report for Build 539802970

• 33 of 38 (86.84%) changed or added relevant lines in 2 files are covered.
• 6 unchanged lines in 2 files lost coverage.
• Overall coverage increased (+0.03%) to 58.138%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
pkg/integrations/legacy/registry.go	0	1	0.0%
pkg/config/envvar/envvar.go	33	37	89.19%

Files with Coverage Reduction	New Missed Lines	%
pkg/metrics/sampler/sampler_routine.go	2	94.74%
pkg/integrations/v4/logs/cfg_watcher.go	4	67.5%

Totals
Change from base Build 518394642:	0.03%
Covered Lines:	11456
Relevant Lines:	19705

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💛 - Coveralls

[noly]

thanks to taking care of this!