Remove apex10000_private variants

When a library is included in two APEXes whose platform_apis settings
are different, two apex variants of the library is created: apex1000 and
apex1000_private.

This change was introduced with ag/15061306, especially by the commit
[1].

However, that part should be reverted because it actually creates
unnecessary variants. It's unnecessary because the two variants of the
library are compiled (excluding the linking) exactly the same. If a
private symbol of its dependency was actually used when compiling the
apex1000_private variant, then the other apex1000 variant wouldn't have
been built because that private symbol must have caused a linkage error.

[1] https://googleplex-android-review.git.corp.google.com/c/platform/build/soong/+/15061306/2..4/android/apex.go#b527).

Bug: 228785792
Test: m
Change-Id: Id58d3e98a51de5e628ca72ef86e9cd11b0ee8971
diff --git a/android/apex_test.go b/android/apex_test.go
index 60a639b..1e2f3bd 100644
--- a/android/apex_test.go
+++ b/android/apex_test.go
@@ -118,17 +118,30 @@
 			},
 		},
 		{
-			name: "don't merge different UsePlatformApis",
+			name: "merge different UsePlatformApis but don't allow using platform api",
 			in: []ApexInfo{
 				{"foo", FutureApiLevel, false, false, nil, []string{"foo"}, []string{"foo"}, nil, NotForPrebuiltApex},
 				{"bar", FutureApiLevel, false, true, nil, []string{"bar"}, []string{"bar"}, nil, NotForPrebuiltApex},
 			},
 			wantMerged: []ApexInfo{
-				{"apex10000_private", FutureApiLevel, false, true, nil, []string{"bar"}, []string{"bar"}, nil, NotForPrebuiltApex},
-				{"apex10000", FutureApiLevel, false, false, nil, []string{"foo"}, []string{"foo"}, nil, NotForPrebuiltApex},
+				{"apex10000", FutureApiLevel, false, false, nil, []string{"bar", "foo"}, []string{"bar", "foo"}, nil, NotForPrebuiltApex},
 			},
 			wantAliases: [][2]string{
-				{"bar", "apex10000_private"},
+				{"bar", "apex10000"},
+				{"foo", "apex10000"},
+			},
+		},
+		{
+			name: "merge same UsePlatformApis and allow using platform api",
+			in: []ApexInfo{
+				{"foo", FutureApiLevel, false, true, nil, []string{"foo"}, []string{"foo"}, nil, NotForPrebuiltApex},
+				{"bar", FutureApiLevel, false, true, nil, []string{"bar"}, []string{"bar"}, nil, NotForPrebuiltApex},
+			},
+			wantMerged: []ApexInfo{
+				{"apex10000", FutureApiLevel, false, true, nil, []string{"bar", "foo"}, []string{"bar", "foo"}, nil, NotForPrebuiltApex},
+			},
+			wantAliases: [][2]string{
+				{"bar", "apex10000"},
 				{"foo", "apex10000"},
 			},
 		},