fix: change name of notation cert file in helmfile

[akashsinghal]

Description

What this PR does / why we need it:

Recent change updated all references of notaryv2 --> notation. This changed the sample notation cert file name. We need to update the helmfile in the quickstart to use this new name.

Which issue(s) this PR fixes (optional, using fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when the PR gets merged):

Fixes #

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Helm Chart Change (any edit/addition/update that is necessary for changes merged to the main branch)
• This change requires a documentation update

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Please also list any relevant details for your test configuration

• Test A
• Test B

Checklist:

• Does the affected code have corresponding tests?
• Are the changes documented, not just with inline documentation, but also with conceptual documentation such as an overview of a new feature, or task-based documentation like a tutorial? Consider if this change should be announced on your project blog.
• Does this introduce breaking changes that would require an announcement or bumping the major version?
• Do all new files have appropriate license header?

Post Merge Requirements

• MAINTAINERS: manually trigger the "Publish Package" workflow after merging any PR that indicates Helm Chart Change

[codecov]

Codecov Report

Patch and project coverage have no change.

Comparison is base (908b2e5) 56.90% compared to head (70ce99d) 56.90%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #975   +/-   ##
=======================================
  Coverage   56.90%   56.90%           
=======================================
  Files          90       90           
  Lines        5272     5272           
=======================================
  Hits         3000     3000           
  Misses       1969     1969           
  Partials      303      303           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[akashsinghal]

@susanshi @binbin-li could I get a review? quickstart is currently broken

[susanshi]

Another scenario where would be nice to have a qutomated quick start test :)