[pkg/ottl]: map literals are not white-space insensitive

[TylerHelmuth]

Not related to this PR, but these examples aren't actually "correct" (unfortunately). it seems the grammar is sensitive to leading spaces after :, which is quite annoying. We should fix that on the grammar IMO.

Originally posted by @edmocosta in #50398 (comment)

[github-actions]

Pinging code owners:

• pkg/ottl: @TylerHelmuth @evan-bradley @edmocosta @bogdandrutu

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[TylerHelmuth]

Specifically this is a yaml issue:

no space:   set(attributes["a"], {"foo":"bar"})   → YAML OK
with space: set(attributes["a"], {"foo": "bar"})  → yaml: line 1: did not find expected key