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GH-37253: [MATLAB] Add test cases which verify that the `NumFields`, `BitWidth`, and `ID` properties can not be modified to `hFixedWidth` test class (#37316)

### Rationale for this change

As @ sgilmore10 pointed out in https://github.com/apache/arrow/pull/37250#discussion_r1298747336, it makes sense to move the tests which verify that the `NumFields`, `BitWidth`, and `ID` properties cannot be set into the `hFixedWidthType` superclass, rather than having these tests implemented in `tTime32Type` and `tTime64Type`, since they are common to all fixed width types.

### What changes are included in this PR?

1. Moved tests which verify that the `BitWidth`, `NumFields`, and `ID` properties cannot be set out of the `tTime32Type` and `tTime64Type` classes and into the superclass `hFixedWidthType`.
2. Fixed typo in `tTime32Type` and `tTime64Type`. Changed variable name `schema` to `type`.

### Are these changes tested?

Yes.

1. Moved tests which verify that the `BitWidth`, `NumFields`, and `ID` properties cannot be set out of the `tTime32Type` and `tTime64Type` classes and into the superclass `hFixedWidthType`.

### Are there any user-facing changes?

No.

This pull request only modifies tests.
* Closes: #37253

Authored-by: Kevin Gurney <kgurney@mathworks.com>
Signed-off-by: Kevin Gurney <kgurney@mathworks.com>