installer: use `-rpcauth` for managed bitcoind #1795

Job	Run time
linter	32s
linter_gui	1m 30s
unit_tests (1.63, ubuntu-latest)	4m 27s
unit_tests (1.63, macOS-latest)	7m 1s
unit_tests (1.63, windows-latest)	5m 48s
unit_tests (nightly, ubuntu-latest)	52s
unit_tests (nightly, macOS-latest)	1m 18s
unit_tests (nightly, windows-latest)	1m 59s
unit_tests_gui (1.65.0, ubuntu-latest)	6m 39s
unit_tests_gui (1.65.0, macOS-latest)	8m 16s
unit_tests_gui (1.65.0, windows-latest)	8m 20s
unit_tests_gui (nightly, ubuntu-latest)	2m 50s
unit_tests_gui (nightly, macOS-latest)	3m 3s
unit_tests_gui (nightly, windows-latest)	4m 50s
	57m 25s

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