Remove codecov badge from README (#4678) #14685

Job	Run time
clang format	38s
python lint check	29s
sanity checks	9s
rustfmt check	17s
clang tidy & clangd diagnostics check	16m 37s
shell test	13m 4s
rust build & test	46m 2s
generate binary dataset	2m 48s
clang build & test	13m 37s
gcc build & test	15m 2s
code coverage	33m 1s
msvc build & test	36m 47s
webassembly build & test	30m 39s
apple clang build & test	4m 53s
macos extension test	43s
clang build & test with page_size_log2=16	4m 51s
clang build & test with page_size_log2=18	9m 21s
gcc build & test in-mem only with various vector size	4m 48s
gcc build & test with asan	26m 13s
linux extension test	20m 51s
benchmark / benchmark	14m 51s
report benchmark result	0s
windows extension test	7m 52s
	5h 3m 33s

Provide feedback