Changing 'Save' button style to primary (#41144) (#41181)

Changing 'Save' button style to primary according to Figma design.

(cherry picked from commit 0599b6180f)

Co-authored-by: Luis Filipe Pessoa <luis.f.pessoa@gmail.com>

public/app/features/alerting/unified/components/rule-editor/AlertRuleForm.tsx

@@ -96,7 +96,7 @@ export const AlertRuleForm: FC<Props> = ({ existing }) => {
             </Button>
           </Link>
           <Button
-            variant="secondary"
+            variant="primary"
             type="button"
             onClick={handleSubmit((values) => submit(values, false), onInvalid)}
             disabled={submitState.loading}