Update max_sdk_version from SdkSpec to ApiLevel

max_sdk_version signifies device version and does not need an sdkKind to
describe it fully. Update the type and cleanup existing usages. As a
side benefit, we also get better error handling since users can no
longer enter something like `public_30` as a valid max_sdk_version in bp
files

Bug: 208456999
Test: no change in ninja file (this should be a no-op)
Test: TH
Change-Id: I304b5ad802bde200137d8e225182828dfd6f7227
diff --git a/java/classpath_fragment.go b/java/classpath_fragment.go
index 45e6175..bc9de50 100644
--- a/java/classpath_fragment.go
+++ b/java/classpath_fragment.go
@@ -136,11 +136,11 @@
 							jar.minSdkVersion = s.minSdkVersion.String()
 						}
 					}
-					if s.maxSdkVersion.ApiLevel.Specified() {
-						if s.maxSdkVersion.ApiLevel.IsCurrent() {
+					if s.maxSdkVersion.Specified() {
+						if s.maxSdkVersion.IsCurrent() {
 							jar.maxSdkVersion = ctx.Config().DefaultAppTargetSdk(ctx).String()
 						} else {
-							jar.maxSdkVersion = s.maxSdkVersion.ApiLevel.String()
+							jar.maxSdkVersion = s.maxSdkVersion.String()
 						}
 					}
 				}