Reject mysql for enterprise advanced (#31164)

* reject MySQL with the enterprise advanced license

If a user attempts to set an Enterprise Advanced License while
configured with MySQL, reject the license. This SKU is not compatible
with MYSQL.

* fix trial typo

* suppress trial banner if MySQL

* Update server/channels/app/platform/license_test.go

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* fix types

* suppress mysql from show start trial modal

* Skip MySQL-incompatible tests for access control and channel banner features

Skip the following tests when running with MySQL database:
- Access control policy tests (create, get, delete, check/test expressions, search, assign/unassign, get channels)
- Channel banner tests in TestPatchChannel and TestCanEditChannelBanner

These features are not supported on MySQL and the tests would fail.
Tests will continue to run normally on PostgreSQL.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

* Skip TestSearchChannelsForAccessControlPolicy subtest for MySQL

Add MySQL skip logic to the "SearchChannelsForAccessControlPolicy with regular user"
subtest as this access control feature is not supported on MySQL.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

* reject trial license requests for MySQL

* return false on sku + mysql match, even if logger is nil

* Fix MySQL trial license tests to skip appropriately based on database driver

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

---------

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
Co-authored-by: Claude <noreply@anthropic.com>

server/channels/api4/license.go

@@ -186,6 +186,12 @@ func requestTrialLicense(c *Context, w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
+	// MySQL is not supported for trial licenses
+	if c.App.Config().SqlSettings.DriverName != nil && *c.App.Config().SqlSettings.DriverName == model.DatabaseDriverMysql {
+		c.Err = model.NewAppError("requestTrialLicense", "api.license.request-trial.mysql.app_error", nil, "mysql is not supported for trial licenses", http.StatusBadRequest)
+		return
+	}
+
 	if c.App.Srv().Platform().LicenseManager() == nil {
 		c.Err = model.NewAppError("requestTrialLicense", "api.license.upgrade_needed.app_error", nil, "", http.StatusForbidden)
 		return