Rationalize logging statements across codebase

This fixes up the following problems:
1. Using string concatenation instead of the formatting variant methods.
2. Logging or swallowing exception messages without logging the exception
   itself (this swallows the stack trace).
3. Unnecessary logging on re-thrown exceptions.
4. Unnecessary use of formatting variant methods when not necessary.
5. Complicated logging statements involving significant processing not being
   wrapped inside of a logging level check.
6. Redundant logging both of an exception itself and its message (this is
   unnecessary duplication).
7. Use of the base Logger class instead of our FormattingLogger class.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=182419837

java/google/registry/ui/server/registrar/RegistrarPaymentAction.java

@@ -177,7 +177,7 @@ public final class RegistrarPaymentAction implements Runnable, JsonAction {
         throw new FormFieldException(CURRENCY_FIELD.name(), "Unsupported currency.");
       }
     } catch (FormFieldException e) {
-      logger.warning(e.toString());
+      logger.warning(e, "Form field error in RegistrarPaymentAction.");
       return JsonResponseHelper.createFormFieldError(e.getMessage(), e.getFieldName());
     }
     Result<Transaction> result =