Remove `MatrixClient.initLegacyCrypto` #10752

Job	Run time
ESLint	42s
Node.js example	29s
Typescript Syntax Check	25s
Analyse Dead Code	19s
JSDoc Checker	42s
Workflow Lint	18s
Downstream tsc element-web	0s
Downstream Typescript Syntax Check	1s
	2m 56s

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