Revert "analyzer: Convert all remaining HintCodes to be WarningCodes"

This reverts commit 7e9e70f.

Reason for revert: Broke flutter customers.

Original change's description:
> analyzer: Convert all remaining HintCodes to be WarningCodes
>
> Fixes #50796
>
> In this change, I only change each previous HintCode to a WarningCode
> by moving it in the YAML file to the WarningCode section. And I change
> each code's `type` from `hint` to `staticWarning`.
>
> This does indicate that the structure of the YAML could be simplified
> to remove the top-level sections like `WarningCode`, but I will let
> someone else make that change independently.
>
> Change-Id: I35c42d9cc8afa9602aadd22143bb32196728f3e5
> Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/467444
> Reviewed-by: Paul Berry <paulberry@google.com>
> Commit-Queue: Samuel Rawlins <srawlins@google.com>

No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Change-Id: Ie9a58321c902965b804a27b166732ee7bf238f5d
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/467881
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Reviewed-by: Alexander Markov <alexmarkov@google.com>
Auto-Submit: Samuel Rawlins <srawlins@google.com>
Commit-Queue: Alexander Markov <alexmarkov@google.com>

Author: srawlins

pkg/analyzer/lib/src/diagnostic/diagnostic.g.dart

@@ -3189,7 +3189,7 @@ deprecatedColonForDefaultValue = DiagnosticWithoutArgumentsImpl(
       "will not be supported in language version 3.0 and later.",
   correctionMessage: "Try replacing the colon with an equal sign.",
   hasPublishedDocs: true,
-  type: DiagnosticType.STATIC_WARNING,
+  type: DiagnosticType.HINT,
   uniqueName: 'deprecated_colon_for_default_value',
   expectedTypes: [],
 );
@@ -3314,7 +3314,7 @@ deprecatedInstantiate = DiagnosticWithArguments(
   expectedTypes: [ExpectedType.object],
 );
 
-/// A warning code indicating reference to a deprecated lint.
+/// A hint code indicating reference to a deprecated lint.
 ///
 /// Parameters:
 /// String ruleName: the rule name
@@ -3332,7 +3332,7 @@ deprecatedLint = DiagnosticWithArguments(
   expectedTypes: [ExpectedType.string],
 );
 
-/// A warning code indicating reference to a deprecated lint.
+/// A hint code indicating reference to a deprecated lint.
 ///
 /// Parameters:
 /// String deprecatedRuleName: the deprecated lint name
@@ -3364,7 +3364,7 @@ deprecatedMemberUse = DiagnosticWithArguments(
   correctionMessage:
       "Try replacing the use of the deprecated member with the replacement.",
   hasPublishedDocs: true,
-  type: DiagnosticType.STATIC_WARNING,
+  type: DiagnosticType.HINT,
   uniqueName: 'deprecated_member_use',
   withArguments: _withArgumentsDeprecatedMemberUse,
   expectedTypes: [ExpectedType.string],
@@ -3382,7 +3382,7 @@ deprecatedMemberUseWithMessage = DiagnosticWithArguments(
   correctionMessage:
       "Try replacing the use of the deprecated member with the replacement.",
   hasPublishedDocs: true,
-  type: DiagnosticType.STATIC_WARNING,
+  type: DiagnosticType.HINT,
   uniqueName: 'deprecated_member_use_with_message',
   withArguments: _withArgumentsDeprecatedMemberUseWithMessage,
   expectedTypes: [ExpectedType.string, ExpectedType.string],
@@ -6769,7 +6769,7 @@ importDeferredLibraryWithLoadFunction = DiagnosticWithoutArgumentsImpl(
       "Try changing the import to not be deferred, or rename the function in "
       "the imported library.",
   hasPublishedDocs: true,
-  type: DiagnosticType.STATIC_WARNING,
+  type: DiagnosticType.HINT,
   uniqueName: 'import_deferred_library_with_load_function',
   expectedTypes: [],
 );
@@ -16341,7 +16341,7 @@ unnecessaryImport = DiagnosticWithArguments(
       "also provided by the import of '{1}'.",
   correctionMessage: "Try removing the import directive.",
   hasPublishedDocs: true,
-  type: DiagnosticType.STATIC_WARNING,
+  type: DiagnosticType.HINT,
   uniqueName: 'unnecessary_import',
   withArguments: _withArgumentsUnnecessaryImport,
   expectedTypes: [ExpectedType.string, ExpectedType.string],