Repurpose Release_Developer BUILDTYPE and remove SK_DEVELOPER.

The Release_Developer build type is now used to build Skia with
release level optimizations but still enable SK_DEBUG. This in turn
means that SkASSERTS and SkRTConf are available in this mode.

Further we can then remove SK_DEVELOPER as a define as it is true
iff SK_DEBUG is true.
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1927583002
DOCS_PREVIEW= https://skia.org/?cl=1927583002

Review-Url: https://codereview.chromium.org/1927583002
diff --git a/tests/RuntimeConfigTest.cpp b/tests/RuntimeConfigTest.cpp
index d40a4f0..b863ee1 100644
--- a/tests/RuntimeConfigTest.cpp
+++ b/tests/RuntimeConfigTest.cpp
@@ -16,12 +16,12 @@
     REPORTER_ASSERT(reporter, 1 == c_RTConfTestVariable);
 
     SK_CONF_SET("test.utils.rtconf.testVariable", 2);
-#ifdef SK_DEVELOPER
+#ifdef SK_DEBUG
     REPORTER_ASSERT(reporter, 2 == c_RTConfTestVariable);
-#else  // not SK_DEVELOPER
-    // Can not change RTConf variables in Release.
+#else  // not SK_DEBUG
+    // Can not change RTConf variables in SK_RELEASE.
     REPORTER_ASSERT(reporter, 1 == c_RTConfTestVariable);
-#endif  // SK_DEVELOPER
+#endif  // SK_DEBUG
 
     // This should not give a warning.
     SK_CONF_TRY_SET("test.utils.rtconf.nonexistentVariable", 7);