Fix various Error Prone errors that were found by the FOSS build

Most common:
- Unnecessary parentheses and operator precedence clarify (self-explanatory)
- Reference equality--there were a few instances of using == or != improperly
- Qualification of Builder (and similar) imports so that it's clear which type of Builder we're referring to
- Marking some immutable classes with @Immutable since EP desires that all enums be deeply immutable
- String.split() having "surprising behavior"

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=230971531

java/google/registry/tools/CanonicalizeLabelsCommand.java

@@ -48,9 +48,10 @@ final class CanonicalizeLabelsCommand implements Command {
   @Override
   public void run() throws IOException {
     Set<String> labels = new TreeSet<>();
-    for (String label : mainParameters.isEmpty()
-        ? CharStreams.readLines(new InputStreamReader(stdin))
-        : Files.readLines(new File(mainParameters.get(0)), UTF_8)) {
+    for (String label :
+        mainParameters.isEmpty()
+            ? CharStreams.readLines(new InputStreamReader(stdin, UTF_8))
+            : Files.readLines(new File(mainParameters.get(0)), UTF_8)) {
       label = label.trim();
       if (label.startsWith("-")) {
         label = label.substring(1);