Fix tekton_pipelines_controller_taskrun_count recount bug

[khrm]

Added before and after condition check to avoid taskrun metrics recount bug.
Fixes #4454

Changes

Submitter Checklist

As the author of this PR, please check off the items in this checklist:

• Docs included if any changes are user facing
• Tests included if any functionality added or changed
• Follows the commit message standard
• Meets the Tekton contributor standards (including
  functionality, content, code)
• Release notes block below has been filled in or deleted (only if no user facing changes)

Release Notes

Fix `tekton_pipelines_controller_taskrun_count recount bug` recount bug which causes an increase in the number of taskrun without any new taskrun execution.

[tekton-robot]

The following is the coverage report on the affected files.
Say /test pull-tekton-pipeline-go-coverage to re-run this coverage report

File	Old Coverage	New Coverage	Delta
pkg/taskrunmetrics/metrics.go	83.6%	83.2%	-0.3

[ghost]

/test pull-tekton-pipeline-alpha-integration-tests

[tekton-robot]

The following is the coverage report on the affected files.
Say /test pull-tekton-pipeline-go-coverage to re-run this coverage report

File	Old Coverage	New Coverage	Delta
pkg/taskrunmetrics/metrics.go	83.6%	83.2%	-0.3

[khrm]

/test pull-tekton-pipeline-integration-tests

[tekton-robot]

The following is the coverage report on the affected files.
Say /test pull-tekton-pipeline-go-coverage to re-run this coverage report

File	Old Coverage	New Coverage	Delta
pkg/taskrunmetrics/metrics.go	83.6%	83.9%	0.3

[tekton-robot]

The following is the coverage report on the affected files.
Say /test pull-tekton-pipeline-go-coverage to re-run this coverage report

File	Old Coverage	New Coverage	Delta
pkg/taskrunmetrics/metrics.go	83.6%	83.9%	0.3

[khrm]

/test pull-tekton-pipeline-integration-tests

[tekton-robot]

The following is the coverage report on the affected files.
Say /test pull-tekton-pipeline-go-coverage to re-run this coverage report

File	Old Coverage	New Coverage	Delta
pkg/reconciler/taskrun/taskrun.go	80.1%	80.1%	-0.0
pkg/taskrunmetrics/metrics.go	83.6%	83.9%	0.3

[tekton-robot]

The following is the coverage report on the affected files.
Say /test pull-tekton-pipeline-go-coverage to re-run this coverage report

File	Old Coverage	New Coverage	Delta
pkg/reconciler/taskrun/taskrun.go	80.1%	80.2%	0.1
pkg/taskrunmetrics/metrics.go	83.6%	83.9%	0.3

[pritidesai]

thank you @khrm 👍

[tekton-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: pritidesai

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[vdemeester]

/lgtm