[7.x] [logstash] remove "upgrade" functionality now that .logstash is a system index (#87056)

[jbudz]

Backport of #87056. The elasticsearch side was recently backported to 7.x - elastic/elasticsearch#66190

[elasticmachine]

Pinging @elastic/kibana-operations (Team:Operations)

[kibanamachine]

💔 Build Failed

• continuous-integration/kibana-ci/pull-request
• Commit: 38ca7dc
• Pipeline Steps (look for red circles / failed steps)
• Interpreting CI Failures

Failed CI Steps

• Jest Integration Tests

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Test Failures

Jest Integration Tests.src/core/server/saved_objects/migrationsv2/integration_tests.migration actions createIndex resolves right after waiting for an index status to be green if the index already existed

Link to Jenkins

Standard Out

Failed Tests Reporter:
  - Test has failed 1 times on tracked branches: https://github.com/elastic/kibana/issues/86350

Stack Trace

ResponseError: null_pointer_exception
    at onBody (/dev/shm/workspace/kibana/node_modules/@elastic/elasticsearch/lib/Transport.js:333:23)
    at IncomingMessage.onEnd (/dev/shm/workspace/kibana/node_modules/@elastic/elasticsearch/lib/Transport.js:260:11)
    at IncomingMessage.emit (events.js:327:22)
    at endReadableNT (internal/streams/readable.js:1327:12)
    at processTicksAndRejections (internal/process/task_queues.js:80:21)

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Metrics [docs]

Module Count

Fewer modules leads to a faster build time

id	before	after	diff
logstash	61	54	-7

Async chunks

Total size of all lazy-loaded chunks that will be downloaded as the user navigates the app

id	before	after	diff
logstash	60.8KB	55.9KB	-4.9KB
triggersActionsUi	1.6MB	1.5MB	-26.9KB
total			-31.8KB

Distributable file count

id	before	after	diff
default	47596	48357	+761

Page load bundle

Size of the bundles that are downloaded on every page load. Target size is below 100kb

id	before	after	diff
logstash	25.9KB	25.6KB	-313.0B
triggersActionsUi	162.5KB	162.6KB	+102.0B
total			-211.0B

Unknown metric groups

async chunk count

id	before	after	diff
triggersActionsUi	31	32	+1

To update your PR or re-run it, just comment with:
@elasticmachine merge upstream

[spalger]

I'll take care of the backport in #87577, thanks!