Cherry-pick to earlgrey_1.0.0: [test] Improve reliability of UART baud rate test #2356

Job	Run time
Lint (quick)	2m 59s
Verible lint	1m 1s
Airgapped build	12m 50s
CW305's Bitstream	22m 27s
Verilated Earl Grey	1h 0m 12s
Lint (slow)	13m 34s
Verilated English Breakfast	7m 48s
Build Docker Containers	2m 43s
Build and test software	13m 2s
Earl Grey for CW310 / Build bitstream	1m 57s
Earl Grey for CW310 Hyperdebug / Build bitstream	1m 57s
Earl Grey for CW340 / Build bitstream	1m 55s
CW310 SiVal ROM_EXT Tests / FPGA test	25m 29s
CW310 SiVal Tests / FPGA test	23m 6s
CW310 ROM_EXT Tests / FPGA test	12m 40s
CW310 Manufacturing Tests / FPGA test	26m 44s
CW310 Test ROM Tests / FPGA test	6m 38s
CW310 ROM_EXT Tests / FPGA test	4m 43s
CW310 ROM Tests / FPGA test	27m 4s
Cache bitstreams to GCP	0s
CW340 Test ROM Tests / FPGA test	2m 30s
CW340 ROM_EXT Tests / FPGA test	2m 1s
CW340 SiVal Tests / FPGA test	13m 2s
CW340 ROM Tests / FPGA test	2m 24s
CW340 Manufacturing Tests / FPGA test	9m 18s
CW340 SiVal ROM_EXT Tests / FPGA test	2m 4s
Verify FPGA jobs	27s
	5h 0m 35s

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