fix nil pointer dereference when taksrun is canceled

[jkhelil]

Changes

When taskrun is status TaskRunCancelled, there is no Status.TaskSpec., the PR aims to fix the test so we dont fall in the nil pointer dereference
here is a status of canceled taskrun

status:
 completionTime: "2024-10-30T01:40:17Z"
 conditions:
 - lastTransitionTime: "2024-10-30T01:40:17Z"
   message: TaskRun "simple-tasks"
     was cancelled. TaskRun cancelled as the PipelineRun it belongs to has timed
     out.
   reason: TaskRunCancelled
   status: "False"
   type: Succeeded
 podName: ""
 startTime: "2024-10-30T01

Submitter Checklist

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

• Has Docs included if any changes are user facing
• Has Tests included if any functionality added or changed
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  functionality, content, code)
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Release Notes

NONE

[lcarva]

/lgtm

[tekton-robot]

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[vdemeester]

/cherry-pick release-v0.22.x

[vdemeester]

/cherry-pick release-v0.21.x

[vdemeester]

/cherry-pick release-v0.22.x

[tekton-robot]

@vdemeester: new pull request created: #1246

In response to this:

/cherry-pick release-v0.22.x

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.

[vdemeester]

/cherry-pick release-v0.21.x

[tekton-robot]

@vdemeester: #1237 failed to apply on top of branch "release-v0.21.x":

Applying: fix nil pointer dereference when taksrun is canceled
Using index info to reconstruct a base tree...
M	pkg/chains/formats/slsa/v1/pipelinerun/pipelinerun.go
Falling back to patching base and 3-way merge...
Auto-merging pkg/chains/formats/slsa/v1/pipelinerun/pipelinerun.go
CONFLICT (content): Merge conflict in pkg/chains/formats/slsa/v1/pipelinerun/pipelinerun.go
error: Failed to merge in the changes.
hint: Use 'git am --show-current-patch=diff' to see the failed patch
Patch failed at 0001 fix nil pointer dereference when taksrun is canceled
When you have resolved this problem, run "git am --continue".
If you prefer to skip this patch, run "git am --skip" instead.
To restore the original branch and stop patching, run "git am --abort".

In response to this:

/cherry-pick release-v0.21.x

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.