[pkg/ottl] Use a setter for Split()

[rockdaboot]

Component(s)

pkg/ottl

What happened?

Description

The profiles signal uses indices + lookup table instead of an array or map.

For example, pprofile.Profile contains a lookup table of attributes (AttributeTable), which is referenced by an array of indices (AttributeIndices).

During the work on the transformprocessor ([draft PR(https://github.com/https://github.com//pull/39036)), it turned out that a typical accessor/getter for attributes would return a pcommon.Map.

Problem

The Split() function doesn't call the target's setter function, so the result is effectively discarded in case of profile attributes.

It means that
set(attributes["test"], Split(attributes["flags"], "|"))
works for logs and metrics, but not for profiles.

Related: #39100

Steps to Reproduce

• Check out [processor/transform] Add support for profiles signal #39036
• uncomment the Split tests in processor/transformprocessor/internal/profiles/processor_test.go at around L305ff
• cd into processor/transformprocessor/internal/profiles/ and run go test ./...

Expected Result

Updated attributes, tests succeed.

Actual Result

Attributes stay unchanged, tests fail.

[github-actions]

Pinging code owners:

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

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[rockdaboot]

Closing this issue as it turned out to be an issue in the attributes setter, which has been fixed with 8f574b3