fix(sdk): fix nested param logic for pl

[Tomcli]

Which issue is resolved by this Pull Request:
Resolves #1046 #1089

Description of your changes:
update logic to fix #1089 with the regex param name instead of the sdk internal param name.

Environment tested:

• Python Version (use python --version):
• Tekton Version (use tkn version):
• Kubernetes Version (use kubectl version):
• OS (e.g. from /etc/os-release):

Checklist:

• The title for your pull request (PR) should follow our title convention. Learn more about the pull request title convention used in this repository.

[yhwang]

/lgtm

[google-oss-prow]

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This pull-request has been approved by: Tomcli, yhwang

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