Bump Go version to 1.23.6 (#30242)

* Bump Go version to 1.23.6

* Update CodeQL Github action as well

* Use server's Go version for CodeQL action

Co-authored-by: Antonis Stamatiou <stamatiou.antonis@gmail.com>

* Empty commit to trigger CI

* Bump golangci-lint to a version supporting Go 1.23

* Fix golangci-lint warnings

Several rules from gosimple, revive and staticcheck linters were
failing:
- Redefinition of built-in identifiers (max, min, new, recover...)
- Use of printf-like functions with simple strings
- Check for nil slices, when len already takes it into account

---------

Co-authored-by: Antonis Stamatiou <stamatiou.antonis@gmail.com>
Co-authored-by: Mattermost Build <build@mattermost.com>

server/channels/app/saml.go

@@ -232,19 +232,19 @@ func (a *App) BuildSamlMetadataObject(idpMetadata []byte) (*model.SamlMetadataRe
 	data := &model.SamlMetadataResponse{}
 	data.IdpDescriptorURL = entityDescriptor.EntityID
 
-	if entityDescriptor.IDPSSODescriptors == nil || len(entityDescriptor.IDPSSODescriptors) == 0 {
+	if len(entityDescriptor.IDPSSODescriptors) == 0 {
 		err := model.NewAppError("BuildSamlMetadataObject", "api.admin.saml.invalid_xml_missing_idpssodescriptors.app_error", nil, "", http.StatusInternalServerError)
 		return nil, err
 	}
 
 	idpSSODescriptor := entityDescriptor.IDPSSODescriptors[0]
-	if idpSSODescriptor.SingleSignOnServices == nil || len(idpSSODescriptor.SingleSignOnServices) == 0 {
+	if len(idpSSODescriptor.SingleSignOnServices) == 0 {
 		err := model.NewAppError("BuildSamlMetadataObject", "api.admin.saml.invalid_xml_missing_ssoservices.app_error", nil, "", http.StatusInternalServerError)
 		return nil, err
 	}
 
 	data.IdpURL = idpSSODescriptor.SingleSignOnServices[0].Location
-	if idpSSODescriptor.SSODescriptor.RoleDescriptor.KeyDescriptors == nil || len(idpSSODescriptor.SSODescriptor.RoleDescriptor.KeyDescriptors) == 0 {
+	if len(idpSSODescriptor.SSODescriptor.RoleDescriptor.KeyDescriptors) == 0 {
 		err := model.NewAppError("BuildSamlMetadataObject", "api.admin.saml.invalid_xml_missing_keydescriptor.app_error", nil, "", http.StatusInternalServerError)
 		return nil, err
 	}