release-notes: add OVS hostname FQDN default change to OSISM 10

[berendt]

Document the upstream kolla-ansible change that switches the openvswitch_hostname default from short hostname to FQDN, and provide the workaround for deployments relying on short hostnames.

AI-assisted: Claude Code

[github-actions]

✅MegaLinter analysis: Success

Descriptor	Linter	Files	Fixed	Errors	Warnings	Elapsed time
✅ ACTION	actionlint	3		0	0	0.03s
✅ JSON	jsonlint	4		0	0	0.16s
✅ JSON	prettier	4		0	0	0.54s
✅ JSON	v8r	4		0	0	6.0s
✅ MARKDOWN	markdownlint	154		0	0	1.84s
✅ MARKDOWN	markdown-table-formatter	154		0	0	0.33s
✅ REPOSITORY	checkov	yes		no	no	15.71s
✅ REPOSITORY	git_diff	yes		no	no	0.02s
✅ REPOSITORY	secretlint	yes		no	no	1.87s
✅ REPOSITORY	trufflehog	yes		no	no	3.93s
✅ SPELL	cspell	183		0	0	5.52s
✅ SPELL	lychee	163		0	0	6.28s
✅ YAML	prettier	5		0	0	0.4s
✅ YAML	v8r	5		0	0	5.86s
✅ YAML	yamllint	5		0	0	0.45s

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• Command: npx mega-linter-runner@9.3.0 --custom-flavor-setup --custom-flavor-linters ACTION_ACTIONLINT,JSON_JSONLINT,JSON_V8R,JSON_PRETTIER,MARKDOWN_MARKDOWNLINT,MARKDOWN_MARKDOWN_TABLE_FORMATTER,REPOSITORY_CHECKOV,REPOSITORY_GIT_DIFF,REPOSITORY_SECRETLINT,REPOSITORY_TRUFFLEHOG,SPELL_CSPELL,SPELL_LYCHEE,YAML_PRETTIER,YAML_YAMLLINT,YAML_V8R