SettingsStore: Change feature_rust_crypto to default true (#12203)

* Set default crypto stack to rust

* Update test for default to rust crypto

* Fix labs settings tests

* Fix test not working with rust crypto

test/components/views/settings/tabs/user/LabsUserSettingsTab-test.tsx

@@ -71,6 +71,25 @@ describe("<LabsUserSettingsTab />", () => {
         });
 
         describe("Not enabled in config", () => {
+            // these tests only works if the feature is not enabled in the config by default?
+            const copyOfGetValueAt = SettingsStore.getValueAt;
+
+            beforeEach(() => {
+                SettingsStore.getValueAt = (
+                    level: SettingLevel,
+                    name: string,
+                    roomId?: string,
+                    isExplicit?: boolean,
+                ) => {
+                    if (level == SettingLevel.CONFIG && name === "feature_rust_crypto") return false;
+                    return copyOfGetValueAt(level, name, roomId, isExplicit);
+                };
+            });
+
+            afterEach(() => {
+                SettingsStore.getValueAt = copyOfGetValueAt;
+            });
+
             it("can be turned on if not already", async () => {
                 // By the time the settings panel is shown, `MatrixClientPeg.initClientCrypto` has saved the current
                 // value to the settings store.