MDL-67673 phpunit: Remove deprecated assertEquals() params

MDL-67673 phpunit: Remove deprecated assertEquals() params

The optional parameters of assertEquals() and assertNotEquals()
are deprecated in PHPUnit 8 (to be removed in PHPUnit 9):

- delta => use assertEqualsWithDelta()
- canonicalize => use assertEqualsCanonicalizing()
- ignoreCase => use assertEqualsIgnoringCase
- maxDepth => removed without replacement.

More info @ https://github.com/sebastianbergmann/phpunit/issues/3341

Initial search done with:

ag 'assert(Not)?Equals\(.*,.*,' --php

Then, running tests and fixing remaining cases.