Restore branch and git sha, to use it in logs and in rageshakes.

Remove quite useless `gitRevisionDate`.

samples/minimal/src/main/kotlin/io/element/android/samples/minimal/Singleton.kt

@@ -37,12 +37,8 @@ object Singleton {
         lowPrivacyLoggingEnabled = false,
         versionName = "0.1.0",
         versionCode = 1,
-        // BuildConfig.GIT_REVISION,
-        gitRevision = "TODO",
-        //  BuildConfig.GIT_REVISION_DATE,
-        gitRevisionDate = "TODO",
-        //  BuildConfig.GIT_BRANCH_NAME,
-        gitBranchName = "TODO",
+        gitRevision = "",
+        gitBranchName = "",
         flavorDescription = "NA",
         flavorShortDescription = "NA",
     )