runtime(java): Stop handpicking syntax groups for @javaTop (#14727)

* runtime(java): Stop handpicking syntax groups for @javaTop

Also:

- Remove the obsolete comment for g:java_allow_cpp_keywords.
- Remove the commented out groups java\%[Debug\]StringError.
- Infer and set the preferred formatting Vim options from
  the modeline.

Since vim-6-0u, non-contained syntax groups can be referred
to by using the "contains=TOP..." argument.

* Set &encoding and &termencoding to "utf-8" for test files

* Limit non-ASCII charset to [§ƒɐɘʬʭΑ-Τα-μ] for test files

Signed-off-by: Aliaksei Budavei <0x000c70@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

runtime/syntax/testdir/input/java_methods_indent2.java

@@ -1,5 +1,5 @@
 // VIM_TEST_SETUP let g:java_highlight_functions = 'indent2'
-
+// VIM_TEST_SETUP set encoding=utf-8 termencoding=utf-8
 
 import java.lang.annotation.ElementType;
 import java.lang.annotation.Target;
@@ -9,12 +9,12 @@ abstract class Indent2MethodsTests
   // TYPES.
   record Τʬ<α>(α a) { }
 
-  enum 𝓔
+  enum E
   {
-    A("𝕬"), B("𝕭"), C("𝕮"), D("𝕯"),
-    E("𝕰"), F("𝕱"), G("𝕲"), H("𝕳");
-    final String 𝐬;
-    private 𝓔(String 𝐬) { this.𝐬 = 𝐬; }
+    A("a"), B("b"), C("c"), D("d"),
+    E("e"), F("f"), G("g"), H("h");
+    final String s;
+    private E(String s) { this.s = s; }
   }
 
   @Target({ElementType.METHOD, ElementType.CONSTRUCTOR})
@@ -50,7 +50,7 @@ abstract class Indent2MethodsTests
   @Tɐggablɘ @Tɐggablɘ abstract void ascii$0_(////////////////
                                                                 );
   @Tɐggablɘ @Tɐggablɘ abstract <α, β> Τʬ<α> μʭʭ$0_(
-                        /* TODO: @SuppressWarnings("bespoke")*/ β 𝛽);
+                        /* TODO: @SuppressWarnings("bespoke")*/ β b);
 
   @Tɐggablɘ private native void ascii$1_(/*////////////*/);
   @Tɐggablɘ private native <α, β> Τʬ<α>[] μʭʭ$1_(
@@ -81,12 +81,12 @@ abstract class Indent2MethodsTests
   public String toString() { return (String) "Indent2MethodsTests"; }
 }
 
-enum 𝓔
+enum E2
 {
-  @SuppressWarnings("bespoke") A("𝗔"),
-  B("𝗕"),
-  C("𝗖"), D("𝗗"),
-  E("𝗘"), F("𝗙"), G("𝗚"), H("𝗛");
-  final String 𝐬;
-  private 𝓔(String 𝐬) { this.𝐬 = 𝐬; }
+  @SuppressWarnings("bespoke") A("a"),
+  B("b"),
+  C("c"), D("d"),
+  E("e"), F("f"), G("g"), H("h");
+  final String s;
+  private E2(String s) { this.s = s; }
 }