Turn on background mapping

[laevandus]

🔗 Issue Links

Resolves ios-issues-tracking/issues/863

🎯 Goal

Set background mapping default to true.

☑️ Contributor Checklist

• I have signed the Stream CLA (required)
• This change follows zero ⚠️ policy (required)
• This change should be manually QAed
• Changelog is updated with client-facing changes
• New code is covered by unit tests
• Comparison screenshots added for visual changes
• Affected documentation updated (docusaurus, tutorial, CMS)

[Stream-SDK-Bot]

StreamChat XCMetrics

target	metric	benchmark	branch	performance	status
MessageList	Hitches total duration	10 ms	1.67 ms	83.3% 🔼	🟢
	Duration	2.6 s	2.55 s	1.92% 🔼	🟢
	Hitch time ratio	4 ms per s	0.65 ms per s	83.75% 🔼	🟢
	Frame rate	79 fps	78.19 fps	1.03% 🔼	🟢
	Number of hitches	1	0.2	80.0% 🔼	🟢
ChannelList	Hitches total duration	12.5 ms	18.36 ms	-46.88% 🔽	🔴
	Duration	2.6 s	2.55 s	1.92% 🔼	🟢
	Hitch time ratio	5 ms per s	7.2 ms per s	-44.0% 🔽	🔴
	Frame rate	76 fps	74.45 fps	2.04% 🔼	🟢
	Number of hitches	1.2	2.0	-66.67% 🔽	🔴

[Stream-SDK-Bot]

StreamChat XCMetrics

target	metric	benchmark	branch	performance	status
MessageList	Hitches total duration	10 ms	6.68 ms	33.2% 🔼	🟢
	Duration	2.6 s	2.55 s	1.92% 🔼	🟢
	Hitch time ratio	4 ms per s	2.6 ms per s	35.0% 🔼	🟢
	Frame rate	79 fps	78.19 fps	1.03% 🔼	🟢
	Number of hitches	1	0.6	40.0% 🔼	🟢
ChannelList	Hitches total duration	12.5 ms	21.7 ms	-73.6% 🔽	🔴
	Duration	2.6 s	2.57 s	1.15% 🔼	🟢
	Hitch time ratio	5 ms per s	8.46 ms per s	-69.2% 🔽	🔴
	Frame rate	76 fps	74.15 fps	2.43% 🔼	🟢
	Number of hitches	1.2	2.4	-100.0% 🔽	🔴

[laevandus]

Ran unit-tests and UI-tests locally.