Revert "linter 1.6."

This reverts commit aa07721aa1.

Reason for revert: breaks google3 (b/191082239)

Original change's description:
> linter 1.6.
>
>
> See also: https://github.com/flutter/flutter/issues/84577 for coordinating breaking change to `sort_directives`.
>
>
> Change-Id: Iefde221bcf9d20d990537d8cfe050aaf381a459f
> Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/203540
> Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
> Commit-Queue: Phil Quitslund <pquitslund@google.com>

TBR=brianwilkerson@google.com,pquitslund@google.com

Change-Id: I148627aa2d8f23c5e1564474909549646b6d65d5
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/203562
Reviewed-by: David Morgan <davidmorgan@google.com>
Commit-Queue: David Morgan <davidmorgan@google.com>

CHANGELOG.md

@@ -89,40 +89,32 @@
 
 #### Linter
 
-Updated the Linter to `1.6.0`, which includes changes that
+Updated the Linter to `1.5.0`, which includes:
 
-- relax `non_constant_identifier_names` to allow for a trailing
-  underscore.
-- fix false negative in `prefer_final_parameters` where first parameter
-  is final.
-- improve `directives_ordering` sorting of directives with dot paths and 
-  dot-separated package names.
-- relax `sort_child_properties_last` to allow for a trailing Widget in
-  instance creations.
-- (internal) migrate to `SecurityLintCode` instead of deprecated
+- (internal) migrated to `SecurityLintCode` instead of deprecated
   `SecurityLintCodeWithUniqueName`.
-- (internal) fix `avoid_types_as_parameter_names` to skip field formal
+- (internal) fixed `avoid_types_as_parameter_names` to skip field formal
   parameters.
-- fix false positives in `prefer_interpolation_to_compose_strings` where
+- fixed false positives in `prefer_interpolation_to_compose_strings` where
   the left operand is not a String.
-- fix false positives in `only_throw_errors` for misidentified type
+- fixed false positives in `only_throw_errors` for misidentified type
   variables.
-- add new lint: `depend_on_referenced_packages`.
+- new lint: `depend_on_referenced_packages`.
 - update `avoid_returning_null_for_future` to skip checks for null-safe
   libraries.
-- add new lint: `use_test_throws_matchers`.
-- relax `sort_child_properties_last` to accept closures after child.
-- improve performance for `prefer_contains` and `prefer_is_empty`.
-- add new lint: `noop_primitive_operations`.
-- mark `avoid_web_libraries_in_flutter` as stable.
-- add new lint: `prefer_final_parameters`.
-- update `prefer_initializing_formals` to allow assignments where identifier
+- new lint: `use_test_throws_matchers`.
+- relaxed `sort_child_properties_last` to accept closures after child.
+- performance improvements for `prefer_contains` and `prefer_is_empty`.
+- new lint: `noop_primitive_operations`.
+- marked `avoid_web_libraries_in_flutter` as stable.
+- new lint: `prefer_final_parameters`.
+- updated `prefer_initializing_formals` to allow assignments where identifier
   names don't match.
-- update `directives_ordering` to checks ordering of `package:` imports in code
+- `directives_ordering` now checks ordering of `package:` imports in code
   outside pub packages.
-- add simple reachability analysis to `use_build_context_synchronously` to
+- simple reachability analysis added to `use_build_context_synchronously` to
   short-circuit await-discovery in terminating blocks.
-- update `use_build_context_synchronously` to recognize nullable types when
+- `use_build_context_synchronously` updated to recognize nullable types when
   accessed from legacy libraries.
 
 #### Pub

DEPS

@@ -125,7 +125,7 @@ vars = {
   "intl_tag": "0.17.0-nullsafety",
   "jinja2_rev": "2222b31554f03e62600cd7e383376a7c187967a1",
   "json_rpc_2_rev": "7e00f893440a72de0637970325e4ea44bd1e8c8e",
-  "linter_tag": "1.6.0",
+  "linter_tag": "1.5.0",
   "lints_tag": "f9670df2a66e0ec12eb51554e70c1cbf56c8f5d0",
   "logging_rev": "e2f633b543ef89c54688554b15ca3d7e425b86a2",
   "markupsafe_rev": "8f45f5cfa0009d2a70589bcda0349b8cb2b72783",