Revert "fix(test): do not allow mixing tests from different types (#29284)"

[mxschmitt]

This reverts commit 4784139.

Closes #29734.

Reason for revert: this original change only covers cases where test.describe() is explicitly called in a file. However, most users have top-level definition of tests without a describe block, so it does not solve both problems it was introduced for:

• mixing hooks and tests, e.g. test1.beforeEach() and test2();
• mixing test1.use() and test2();
• forcing different workers inside a single file/suite because of different worker fixtures between test1() and test2().

[github-actions]

Test results for "tests 1"

35856 passed, 619 skipped
✔️✔️✔️

Merge workflow run.