[7.11] [test/functional_cors] 9000 is sometimes in use, make getPort random (#87050)

[spalger]

Backports the following commits to 7.11:

• [test/functional_cors] 9000 is sometimes in use, make getPort random ([test/functional_cors] 9000 is sometimes in use, make getPort random #87050)

[kibanamachine]

💚 Build Succeeded

• continuous-integration/kibana-ci/pull-request
• Commit: eb1d5d3

Metrics [docs]

Async chunks

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

id	before	after	diff
triggersActionsUi	1.5MB	1.5MB	-26.9KB

Distributable file count

id	before	after	diff
default	47630	48393	+763

Page load bundle

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

id	before	after	diff
triggersActionsUi	162.0KB	162.1KB	+102.0B

Unknown metric groups

async chunk count

id	before	after	diff
triggersActionsUi	31	32	+1

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