Sort by label keys before generating labels key and value lists

[soundofspace]

Description

Fixes bug where labels are wrongfully assigned to values because their order changed in input dictionary.

Fixes part of #3391. This does not fix missing labels, it only fixes the issue of labels being wrongfully assigned even if all labels are present (also empty string label values).

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

Test metric:

test_counter.add(1, {'cause': 'cause1', 'reason': 'reason1'})
test_counter.add(1, {'reason': 'reason2', 'cause': 'cause2'})

Before:

# HELP test_counter_total counter used for testing
# TYPE test_counter_total counter
test_counter_total{cause="reason1",reason="cause1"} 1.0
# HELP test_counter_total counter used for testing
# TYPE test_counter_total counter
test_counter_total{cause="cause2",reason="reason2"} 1.0

After:

# HELP test_counter_total counter used for testing
# TYPE test_counter_total counter
test_counter_total{cause="cause1",reason="reason1"} 1.0
test_counter_total{cause="cause2",reason="reason2"} 1.0

Does This PR Require a Contrib Repo Change?

• No.

Checklist:

• Followed the style guidelines of this project
• Changelogs have been updated -> where?

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: lzchen / name: Leighton Chen (4c5a2a0, 970679c)
• ✅ login: soundofspace (f676245, 364f704, 729aa22, 6a2fe89, 18308db, 3f97bac, 2c526cd, 19916f6, 9f8046f, 833acee)
• ✅ login: ocelotl / name: Diego Hurtado (ef6fd85)

[ocelotl]

Can you please add a test case?

[ocelotl]

@lzchen

[lzchen]

Please add a changelog entry and a test for this.

[ocelotl]

@soundofspace this PR needs a test case, marking it as a draft until it has been added.

[xrmx]

Given it's a trivial change and still an improvement compared to the actual code for some use cases LGTM

[lzchen]

LGTM. Please fix failing build.

[soundofspace]

@lzchen not really sure why that build is failing because of this pr, seems like something unrelated to this, and not really sure how to fix it.

[ocelotl]

@lzchen not really sure why that build is failing because of this pr, seems like something unrelated to this, and not really sure how to fix it.

Probably we just need to update the contrib test SHA, no worries, I have done so.