Move DbLogTest::verifyCron to a kernel test

Here is a patch.

I'd like to highlight:
1) was changed $cron_count = 1 to $cron_count == 1 which is more correct.
2) was renamed verifyCron to testDbLogCron.

I'm curious whether we should improve the code while porting it to a kernel test or not.

1. +++ b/core/modules/dblog/tests/src/Kernel/DbLogTest.php
   @@ -0,0 +1,129 @@
   +    $this->assertTrue($count > $row_limit, format_string('Dblog row count of @count exceeds row limit of @limit', ['@count' => $count, '@limit' => $row_limit]));
   

   You could use assertGreaterThan here

2. +++ b/core/modules/dblog/tests/src/Kernel/DbLogTest.php
   @@ -0,0 +1,129 @@
   +    $this->assertTrue($cron_detailed_count == $module_count + 2, format_string('Cron added @count of @expected new log entries', ['@count' => $cron_detailed_count, '@expected' => $module_count + 2]));
   

   You could use assertEquals here

3. +++ b/core/modules/dblog/tests/src/Kernel/DbLogTest.php
   @@ -0,0 +1,129 @@
   +    $this->assertTrue($cron_count == 1, format_string('Cron added @count of @expected new log entries', ['@count' => $cron_count, '@expected' => 1]));
   

   You could use assertEquals here as well

thanks for your review. I'm always want to improve smth here :). Then I read this:

Otherwise try to change as little as possible in the converted web test. Do not get tempted to "improve" or "tidy up" the tests - the conversion should be easy to review with only the minimum necessary changes. Further cleanup can be done in a follow-up issue.

and try to convert with minimal changes. Anyways, Here is improved patch.

This needs #2985701: Followup: Move DbLogTest::generateLogEntries() into a Trait first as $this->adminUser is not set during the kernel test.

#2985701: Followup: Move DbLogTest::generateLogEntries() into a Trait was committed as well :)
Here is a patch

Looks good to me.

Committed and pushed 41b994cc88 to 8.7.x and 9130e65fbe to 8.6.x. Thanks!

Backported to 8.6.x since this is a test only change.