Moved string-formatting methods from Slog to Slogf.

Slog is a core class provided by frameworks.jar, and these new methods
were causing performance regressions, so they were moved to a
system_server only class.

Bug: 182476140
Bug: 183523451

Test: atest --rebuild-module-info FrameworksMockingServicesTests:SLogfTest

Change-Id: I98cbb122d5410b61812edc85162aa6b10b995fdc
diff --git a/services/Android.bp b/services/Android.bp
index c160842..81bb579 100644
--- a/services/Android.bp
+++ b/services/Android.bp
@@ -66,6 +66,11 @@
     visibility: ["//visibility:private"],
 }
 
+java_library {
+    name: "Slogf",
+    srcs: ["core/java/com/android/server/utils/Slogf.java"],
+}
+
 // merge all required services into one jar
 // ============================================================
 java_library {