fix(@angular/build): exclude .angular from coverage instrumentation

[cexbrayat]

PR Checklist

Please check to confirm your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/angular/angular-cli/blob/main/CONTRIBUTING.md#-commit-message-guidelines
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Documentation content changes
• Other... Please describe:

What is the current behavior?

Running ng test --code-coverage in a CLI project curently generates:

--------------------------------------------------|---------|----------|---------|---------|-------------------
File                                              | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s 
--------------------------------------------------|---------|----------|---------|---------|-------------------
All files                                         |   31.16 |       50 |      50 |   31.16 |                   
 .angular/cache/21.0.0-next.4/vitest-coverage/vite/deps |       0 |        0 |       0 |       0 |                   
  @angular_core.js                                |       0 |        0 |       0 |       0 | 1-497             
  chunk-WDMUDEB6.js                               |       0 |        0 |       0 |       0 | 1-51              
 src/app                                          |     100 |      100 |     100 |     100 |                   
  app.ts                                          |     100 |      100 |     100 |     100 |                   
 src/app/menu                                     |     100 |       75 |     100 |     100 |                   
  menu.ts                                         |     100 |       75 |     100 |     100 | 9                 
--------------------------------------------------|---------|----------|---------|---------|-------------------

What is the new behavior?

The instrumentation filter now excludes files in the .angular directory in addition to node_modules.

Does this PR introduce a breaking change?

• Yes
• No

Other information