[toolchain] Enable LLD, LTO and minsize by default #6355

Job	Run time
Lint (quick)	3m 47s
Lint (slow)	11m 55s
Airgapped build	12m 24s
Build documentation	5m 22s
CW305's Bitstream	2m 29s
Run OTBN crypto tests	2m 41s
Run OTBN smoke Test	2m 45s
Verible lint	1m 6s
Verilated Earl Grey	1h 4m 55s
Verilated English Breakfast	3m 39s
Build Docker Containers	2m 41s
QEMU smoketest	2m 28s
Build and test Darjeeling software	4m 18s
Build and test software	20m 13s
Earl Grey for CW310 / Build bitstream	1h 5m 0s
Earl Grey for CW310 Hyperdebug / Build bitstream	1h 4m 55s
Earl Grey for CW340 / Build bitstream	1h 29m 37s
CW310 ROM Tests / FPGA test	39m 20s
CW310 Test ROM Tests / FPGA test	4m 3s
CW310 SiVal ROM_EXT Tests / FPGA test	32m 53s
Hyper310 ROM_EXT Tests / FPGA test	13m 5s
CW310 Manufacturing Tests / FPGA test	26m 18s
CW310 SiVal Tests / FPGA test	23m 53s
Cache bitstreams to GCP	0s
CW340 Test ROM Tests / FPGA test	3m 18s
CW340 ROM_EXT Tests / FPGA test	4m 38s
CW340 Manufacturing Tests / FPGA test	2m 16s
CW340 ROM Tests / FPGA test	42s
CW340 SiVal Tests / FPGA test	2m 23s
CW340 SiVal ROM_EXT Tests / FPGA test	3m 54s
Verify FPGA jobs	29s
	8h 37m 27s

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