Update gl-text-gray-500 to gl-text-subtle

...vascripts/admin/abuse_report/components/labels_select.vue

...ipts/analytics/shared/components/date_ranges_dropdown.vue

.../analytics/shared/components/projects_dropdown_filter.vue

...assets/javascripts/boards/components/board_card_inner.vue

...ssets/javascripts/boards/components/board_list_header.vue

...scripts/boards/components/sidebar/board_editable_item.vue

...pts/ci/catalog/components/list/ci_resources_list_item.vue

...vascripts/ci/pipeline_mini_graph/downstream_pipelines.vue

...ascripts/ci/pipeline_new/components/pipeline_new_form.vue

...javascripts/ci/pipelines_page/components/pipeline_url.vue

app/assets/javascripts/clusters_list/constants.js

...cripts/content_editor/components/suggestions_dropdown.vue

...components/contribution_event/contribution_event_base.vue

..._management/components/design_notes/design_discussion.vue

...avascripts/design_management/components/toolbar/index.vue

...sets/javascripts/diffs/components/diff_line_note_form.vue

app/assets/javascripts/diffs/components/diff_stats.vue

...assets/javascripts/environments/components/deployment.vue

...vascripts/environments/components/environment_actions.vue

app/assets/javascripts/environments/constants.js