Remove core_lib property from java_sdk_library

Its not used, remove it.

Bug: 186723288
Test: TestJavaSdkLibraryDist
Change-Id: I1689b670a8ae6a614e5e4ec5e79cb5e283b2e277

java/sdk_library_test.go

@@ -871,13 +871,6 @@ func TestJavaSdkLibraryDist(t *testing.T) {
 			srcs: ["foo.java"],
 			dist_stem: "foo",
 		}
-
-		java_sdk_library {
-			name: "sdklib_core_lib",
-			unsafe_ignore_missing_latest_api: true,
-			srcs: ["foo.java"],
-			core_lib: true,
-		}
 	`)
 
 	type testCase struct {
@@ -907,11 +900,6 @@ func TestJavaSdkLibraryDist(t *testing.T) {
 			distDir:  "apistubs/unknown/public",
 			distStem: "foo.jar",
 		},
-		{
-			module:   "sdklib_core_lib",
-			distDir:  "apistubs/core/public",
-			distStem: "sdklib_core_lib.jar",
-		},
 	}
 
 	for _, tt := range testCases {