Revert^2 "Enable String compression."

Test: m test-art-host (interpreter, JIT, AOT)
Test: m test-art-target on Nexus 6P (interpreter, JIT, AOT)
Test: Nexus 6P boots
Test: m ahat-test
Bug: 31040547

This reverts commit afcb365b2d3ae152989826c2afb0d98a9cf3f6be.

Change-Id: Id7e27d717c8e36d3c7abdde59ca2c8fd4fc221c9
diff --git a/runtime/mirror/string.h b/runtime/mirror/string.h
index 35ce98e..dbb5a4c 100644
--- a/runtime/mirror/string.h
+++ b/runtime/mirror/string.h
@@ -32,7 +32,7 @@
 namespace mirror {
 
 // String Compression
-static constexpr bool kUseStringCompression = false;
+static constexpr bool kUseStringCompression = true;
 enum class StringCompressionFlag : uint32_t {
     kCompressed = 0u,
     kUncompressed = 1u