Fix to use target dsp in script run rollback

[ffjlabo]

What this PR does / why we need it:

Fixed to use TargetDSP on the SCRIPT_RUN_ROLLBACK stage. With these fixes, we can refer to the files located in the app dir when executing the SCRIPT_RUN_ROLLBACK stage.

I chose TargetDSP, not RunningDSP, because the commands on the onRollback are set in app.pipecd.yaml used when Deployment is executed. The purpose of the SCRIPT_RUN_ROLLBACK stage is to run whatever command is currently set in onRollback during rollback.

Which issue(s) this PR fixes:

Part of #5214

Does this PR introduce a user-facing change?:

• How are users affected by this change:
• Is this breaking change:
• How to migrate (if breaking change):

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 0% with 9 lines in your changes missing coverage. Please review.

Project coverage is 22.82%. Comparing base (5d3e17d) to head (8ffadca).

Files with missing lines	Patch %	Lines
pkg/app/piped/executor/kubernetes/rollback.go	0.00%	7 Missing :warning:
pkg/app/piped/deploysource/deploysource.go	0.00%	1 Missing :warning:
pkg/app/pipedv1/deploysource/deploysource.go	0.00%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #5215 +/- ## ======================================= Coverage 22.82% 22.82% ======================================= Files 420 420 Lines 45302 45309 +7 ======================================= + Hits 10340 10344 +4 - Misses 34166 34170 +4 + Partials 796 795 -1 ```

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