[8.6] [Fleet] Fix max 20 installed integrations returned from Fleet API (#150780)

[kpollich]

Backport

This will backport the following commits from main to 8.6:

• [Fleet] Fix max 20 installed integrations returned from Fleet API (#150780)

Questions ?

Please refer to the Backport tool documentation

\n\n### Questions ?\nPlease refer to the [Backport tool\ndocumentation](https://github.com/sqren/backport)\n\n\n\nCo-authored-by: Kyle Pollich "}},{"branch":"main","label":"v8.8.0","labelRegex":"^v8.8.0$","isSourceBranch":true,"state":"MERGED","url":"https://github.com//pull/150780","number":150780,"mergeCommit":{"message":"[Fleet] Fix max 20 installed integrations returned from Fleet API (#150780)\n\n## Summary\r\n\r\nFix an (old) bug where Fleet's \"list packages\" API endpoint would only\r\never return 20 installed integrations at most.\r\n\r\nI haven't included a test case here because I'm not sure we have 20 test\r\npackages that can reasonably be installed at the same time. Also feels\r\nlike an arbitrary number to introduce a \"lists all packages even if\r\nthere are more N\" test case. Open to feedback on testing.\r\n\r\n## Before\r\n\r\n23 installed integrations, only 20 in UI\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n## After\r\n\r\n23 installed integrations, 23 in UI\r\n\r\n\r\n","sha":"e7209f52a91170ce3e53d2bd27bafaecf6195d54"}}]}] BACKPORT-->

[kibana-ci]

💚 Build Succeeded

• Buildkite Build
• Commit: fce6cf8

Metrics [docs]

Unknown metric groups

ESLint disabled in files

id	before	after	diff
osquery	1	2	+1

ESLint disabled line counts

id	before	after	diff
enterpriseSearch	19	21	+2
fleet	61	67	+6
osquery	108	113	+5
securitySolution	441	447	+6
total			+19

Total ESLint disabled count

id	before	after	diff
enterpriseSearch	20	22	+2
fleet	69	75	+6
osquery	109	115	+6
securitySolution	518	524	+6
total			+20

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@elasticmachine merge upstream