[5.1] replace app property in SEF plugin

[heelc29]

Followup Pull Request for PRs #42702 and #42704 . @Hackwar

Summary of Changes

replace extra app property and replace with injected application due service provider

Testing Instructions

check new options (#42702 and #42704) are still working as expected

Actual result BEFORE applying this Pull Request

app property in plugins are deprecated

joomla-cms/libraries/src/Plugin/CMSPlugin.php

Lines 137 to 145 in 8da0b7c

	if (property_exists($this, 'app')) {
	@trigger_error('The application should be injected through setApplication() and requested through getApplication().', E_USER_DEPRECATED);
	$reflection = new \ReflectionClass($this);
	$appProperty = $reflection->getProperty('app');
	if ($appProperty->isPrivate() === false && \is_null($this->app)) {
	$this->app = Factory::getApplication();
	}
	}

Expected result AFTER applying this Pull Request

no deprecated app property is used in sef plugin

Link to documentations

Please select:

• No documentation changes for docs.joomla.org needed
• No documentation changes for manual.joomla.org needed

[Quy]

#42932 includes these fixes.