Remove redundant $message from assert(Not)InstanceOf calls

Problem/Motivation

In #3128905: Replace assert* involving an instanceof operator with assertInstanceOf()/assertNotInstanceOf(), we standardized across standard PHPUnit's assert(Not)InstanceOf calls to check if an object is implementing a specific class.

Many of the conversion done there are from legacy Simpletest assertions, when it was normal to add a message to the assertion.

However:
1) In Simpletest, the message was a description of what the assertion was checking, so that in the Simpletest UI this could be visually presented as a result of the test run. In PHPUnit, on the contrary, the message is a description of the failure occurred while testing, so that it can be presented in the log and then test execution stops.
In the conversion, the messages should be 'negated', for example:

$this->assertInstanceOf(ViewExecutable::class, $factory->get($view), 'A ViewExecutable instance was returned from the factory.');

For Simpletest the message was OK, but in PHPUnit, if the assertion fails, it would be because the $factory->get($view) is NOT an instance of ViewExecutable::class, so the message should be, really, 'The object returned from the factory was not an instance of ViewExecutable.'

So to say that in HEAD currently the messages were not adjusted as part of conversions and are in many cases misleading in case of test failures.

2) The standard message generated by PHPUnit in case of failure of an assert(Not)InstanceOf is probably more than enough in 99% of the cases. GIven the case above, failure of

$this->assertInstanceOf(ViewExecutable::class, $factory->get($view));

will return something like

$ phpunit InstanceOfTest
PHPUnit 9.0.0 by Sebastian Bergmann and contributors.

F

Time: 0 seconds, Memory: 5.00Mb

There was 1 failure:

1) InstanceOfTest::testFailure
Failed asserting that 'WhateverClass" Object (...) is an instance of class "ViewExecutable".

/home/sb/InstanceOfTest.php:6

FAILURES!
Tests: 1, Assertions: 1, Failures: 1.  

Proposed resolution

Just remove all the $message arguments from assert(Not)InstanceOf calls and rely on standard PHPUnit messaging. Also it's not necessary to move the string to a comment since it's pretty clear from reading the code what is being checked.

Deviate from above only when it's clear a bespoke message would add value.

Discovery regex:

assert(?:Not)?InstanceOf\(.*,.*,.*[\'"]

Remaining tasks

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