refactor: FormatRulesTest and StrictRules\FormatRulesTest

[kenjis]

Description

• use inheritance

Before:

$ ./phpunit tests/system/Validation/FormatRulesTest.php
PHPUnit 9.5.25 #StandWithUkraine

Runtime:       PHP 8.1.11
Configuration: /Users/kenji/work/codeigniter/official/CodeIgniter4/phpunit.xml

...............................................................  63 / 193 ( 32%)
............................................................... 126 / 193 ( 65%)
............................................................... 189 / 193 ( 97%)
....                                                            193 / 193 (100%)

Time: 00:00.888, Memory: 16.00 MB

OK (193 tests, 193 assertions)

$ ./phpunit tests/system/Validation/StrictRules/FormatRulesTest.php
PHPUnit 9.5.25 #StandWithUkraine

Runtime:       PHP 8.1.11
Configuration: /Users/kenji/work/codeigniter/official/CodeIgniter4/phpunit.xml

...............................................................  63 / 198 ( 31%)
............................................................... 126 / 198 ( 63%)
............................................................... 189 / 198 ( 95%)
.........                                                       198 / 198 (100%)

Time: 00:00.953, Memory: 16.00 MB

OK (198 tests, 198 assertions)

After:

$ ./phpunit tests/system/Validation/FormatRulesTest.php
PHPUnit 9.5.25 #StandWithUkraine

Runtime:       PHP 8.1.11
Configuration: /Users/kenji/work/codeigniter/official/CodeIgniter4/phpunit.xml

...............................................................  63 / 195 ( 32%)
............................................................... 126 / 195 ( 64%)
............................................................... 189 / 195 ( 96%)
......                                                          195 / 195 (100%)

Time: 00:01.352, Memory: 16.00 MB

OK (195 tests, 195 assertions)

$ ./phpunit tests/system/Validation/StrictRules/FormatRulesTest.php
PHPUnit 9.5.25 #StandWithUkraine

Runtime:       PHP 8.1.11
Configuration: /Users/kenji/work/codeigniter/official/CodeIgniter4/phpunit.xml

...............................................................  63 / 199 ( 31%)
............................................................... 126 / 199 ( 63%)
............................................................... 189 / 199 ( 94%)
..........                                                      199 / 199 (100%)

Time: 00:01.005, Memory: 16.00 MB

OK (199 tests, 199 assertions)

Checklist:

• Securely signed commits
• [] Component(s) with PHPDoc blocks, only if necessary or adds value
• [] Unit testing, with >80% coverage
• [] User guide updated
• Conforms to style guide