CI consistently put `|` at start of line in pygrep hooks
Currently, the pygrep hooks have the "or" `|` symbol at the end of the line, which makes diffs longer than necessary and can cause bugs. It would be better to put that symbol at the beginning of the line.

For example, instead of
```
    -   id: non-standard-numpy.random-related-imports
        name: Check for non-standard numpy.random-related imports excluding pandas/_testing.py
        language: pygrep
        exclude: pandas/_testing.py
        entry: |
            (?x)
            # Check for imports from np.random.<method> instead of `from numpy import random` or `from numpy.random import <method>`
            from\ numpy\ import\ random|
            from\ numpy.random\ import
```

it should be
```
    -   id: non-standard-numpy.random-related-imports
        name: Check for non-standard numpy.random-related imports excluding pandas/_testing.py
        language: pygrep
        exclude: pandas/_testing.py
        entry: |
            (?x)
            # Check for imports from np.random.<method> instead of `from numpy import random` or `from numpy.random import <method>`
            from\ numpy\ import\ random
            |from\ numpy.random\ import
```

There's even an `|` symbol missing in the `non-standard-imports-in-tests`, which should be fixed (having the symbol at the beginning of the line would probably have made this easier to spot)

The file that needs changing is `.pre-commit-config.yaml`