Clean up whitespace in deprecation yamls

To get yamllint to start scanning these files,
we need to fix all the whitespace warnings
and errors

data/deprecations/14-3-deprecation_omniauth-kerberos_gem.yml

@@ -14,4 +14,3 @@
   tiers: [Premium, Ultimate]
   issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/337384
   documentation_url: https://docs.gitlab.com/ee/integration/kerberos.html#upgrading-from-password-based-to-ticket-based-kerberos-sign-ins
-

data/deprecations/14-8-Elasticsearch-6-8.yml

@@ -15,4 +15,3 @@
   tiers: [Premium, Ultimate]
   issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/350275
   documentation_url: https://docs.gitlab.com/ee/integration/elasticsearch.html#version-requirements
-

data/deprecations/15-0-deprecate-monitor-logging.yml

@@ -13,4 +13,3 @@
   documentation_url: https://docs.gitlab.com/ee/operations/#aggregate-and-store-logs-deprecated # (optional) This is a link to the current documentation page
   image_url:  # (optional) This is a link to a thumbnail image depicting the feature
   video_url:  # (optional) Use the youtube thumbnail URL with the structure of https://img.youtube.com/vi/UNIQUEID/hqdefault.jpg
-

data/deprecations/15-0-deprecate-monitor-metrics.yml

@@ -14,4 +14,3 @@
   documentation_url: https://docs.gitlab.com/ee/operations/metrics/dashboards/ # (optional) This is a link to the current documentation page
   image_url:  # (optional) This is a link to a thumbnail image depicting the feature
   video_url:  # (optional) Use the youtube thumbnail URL with the structure of https://img.youtube.com/vi/UNIQUEID/hqdefault.jpg
-