remove unconverted strip_import_prefix property

The requirements for this property changed in aosp/1985613.

Test: go test ./bp2build
Change-Id: If75daf11c857cdd8a54c119e073e327cddf8543d
diff --git a/bp2build/java_proto_conversion_test.go b/bp2build/java_proto_conversion_test.go
index 93b0677..61a398c 100644
--- a/bp2build/java_proto_conversion_test.go
+++ b/bp2build/java_proto_conversion_test.go
@@ -71,8 +71,7 @@
 }`
 
 	protoLibrary := makeBazelTarget("proto_library", "java-protos_proto", attrNameToString{
-		"srcs":                `["a.proto"]`,
-		"strip_import_prefix": `""`,
+		"srcs": `["a.proto"]`,
 	})
 
 	for _, tc := range testCases {
@@ -107,8 +106,7 @@
 `,
 		expectedBazelTargets: []string{
 			makeBazelTarget("proto_library", "java-protos_proto", attrNameToString{
-				"srcs":                `["a.proto"]`,
-				"strip_import_prefix": `""`,
+				"srcs": `["a.proto"]`,
 			}),
 			makeBazelTarget(
 				"java_lite_proto_library",