[main] support startingDeadlineSeconds configuration in pruner cron jobs

[jkandasa]

Changes

• Fixes: SRVKP-4277 - Inclusion of configuration parameter "startingDeadlineSeconds" in TektonConfig
• Added support to startingDeadlineSeconds in pruner cron jobs

Example in TektonConfig CR:

pruner:
  schedule: "0 8 * * *"
  startingDeadlineSeconds: 100 # optional
  resources:
    - taskrun
    - pipelinerun
  keep: 3

NOTE: under pruner config all the existing fields are in snake_case. Cron Job has spec.startingDeadlineSeconds as camelCase, to have the consistency across, using startingDeadlineSeconds as camelCase.

Submitter Checklist

These are the criteria that every PR should meet, please check them off as you
review them:

• Run make test lint before submitting a PR
• Includes tests (if functionality changed/added)
• Includes docs (if user facing)
• Commit messages follow commit message best practices

See the contribution guide for more details.

Release Notes

`startingDeadlineSeconds` configuration support added to pruner cron jobs via TektonConfig CR

[tekton-robot]

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

File	Old Coverage	New Coverage	Delta
pkg/reconciler/common/prune.go	89.4%	89.7%	0.3

[piyush-garg]

/lgtm

[tekton-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: vdemeester

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• OWNERS [vdemeester]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment