fix(theming): Don't reset the cachebuster value when we reset theming

[SystemKeeper]

• Resolves cypress failures after merge of perf: Set session.cache_limiter at runtime to avoid clients caching static assets served by PHP #46320

Summary

From the other PR:

By default there is a Pragma: no-cache header set due to the default
value no-cache of session.cache-limiter, which will cause Chrome and
iOS to not cache even with a different Cache-Control header set on the
response.

After the PR was merged the cypress-tests theming/AdminSettings kept failing. Since we now don't have a pragma: no-cache header anymore, we now rely on cache-control header and our cachebuster implementation to make sure that we get the correct files. For some files, we rely on a cachebuster based on appVersion and cachebuster value:

server/lib/private/TemplateLayout.php

Lines 298 to 331 in b97c7df

	protected function getVersionHashSuffix($path = false, $file = false) {
	if ($this->config->getSystemValueBool('debug', false)) {
	// allows chrome workspace mapping in debug mode
	return "";
	}
	$themingSuffix = '';
	$v = [];
	if ($this->config->getSystemValueBool('installed', false)) {
	if (\OC::$server->getAppManager()->isInstalled('theming')) {
	$themingSuffix = '-' . $this->config->getAppValue('theming', 'cachebuster', '0');
	}
	$v = \OC_App::getAppVersions();
	}
	// Try the webroot path for a match
	if ($path !== false && $path !== '') {
	$appName = $this->getAppNamefromPath($path);
	if (array_key_exists($appName, $v)) {
	$appVersion = $v[$appName];
	return '?v=' . substr(md5($appVersion), 0, 8) . $themingSuffix;
	}
	}
	// fallback to the file path instead
	if ($file !== false && $file !== '') {
	$appName = $this->getAppNamefromPath($file);
	if (array_key_exists($appName, $v)) {
	$appVersion = $v[$appName];
	return '?v=' . substr(md5($appVersion), 0, 8) . $themingSuffix;
	}
	}
	return '?v=' . self::$versionHash . $themingSuffix;
	}

To make sure individual tests are reliable, we reset the theming settings completely before each test:

server/apps/theming/lib/ThemingDefaults.php

Lines 439 to 442 in b97c7df

	public function undoAll(): void {
	$this->config->deleteAppValues('theming');
	$this->increaseCacheBuster();
	}

This also results in a removed cachebuster value and therefore we get the same urls in different tests which (with the changes of the other PR) results in electron to use a cached version of the file, instead of requesting the latest one.
To fix this, we keep the cachebuster value when resetting theming and increase it afterwards.

TODO

• Don't increase twice

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• Tests (unit, integration, api and/or acceptance) are included
• Screenshots before/after for front-end changes
• Documentation (manuals or wiki) has been updated or is not required
• Backports requested where applicable (ex: critical bugfixes)

[SystemKeeper]

/backport to stable29

[SystemKeeper]

/backport to stable28