Use mirrors for ubuntu apt source (#60216)
Summary:
Fixes https://github.com/pytorch/pytorch/issues/60135
Experimented on circleci
https://app.circleci.com/pipelines/github/zhouzhuojie/gha-ci-playground/7/workflows/965c95b8-2186-434a-92ca-9cd9c8aaafdc/jobs/7
Sample logs
```
Need to get 1,389 kB of archives.
After this operation, 5,495 kB of additional disk space will be used.
Get:1 http://mirrors.ubuntu.com/mirrors.txt Mirrorlist [3,270 B]
Get:2 http://mirror.lstn.net/ubuntu focal/main amd64 libtcl8.6 amd64 8.6.10+dfsg-1 [902 kB]
Get:7 http://ubuntu.securedservers.com focal/main amd64 libipc-run-perl all 20180523.0-2 [89.7 kB]
Get:5 http://mirrors.edge.kernel.org/ubuntu focal/universe amd64 expect amd64 5.45.4-2build1 [137 kB]
Get:4 http://mirror.pnl.gov/ubuntu focal/universe amd64 tcl-expect amd64 5.45.4-2build1 [105 kB]
Get:6 http://mirror.lstn.net/ubuntu focal/main amd64 libio-pty-perl amd64 1:1.12-1 [32.4 kB]
Get:9 https://mirrors.bloomu.edu/ubuntu focal/main amd64 libtimedate-perl all 2.3200-1 [34.0 kB]
Get:8 http://la-mirrors.evowise.com/ubuntu focal/universe amd64 libtime-duration-perl all 1.21-1 [13.1 kB]
Get:3 http://mirrors.ocf.berkeley.edu/ubuntu focal/main amd64 tcl8.6 amd64 8.6.10+dfsg-1 [14.8 kB]
Get:10 http://mirrors.ocf.berkeley.edu/ubuntu focal/universe amd64 moreutils amd64 0.63-1 [60.5 kB]
Fetched 1,392 kB in 3s (464 kB/s)
```
Pull Request resolved: https://github.com/pytorch/pytorch/pull/60216
Reviewed By: seemethere
Differential Revision: D29214661
Pulled By: zhouzhuojie
fbshipit-source-id: ed2d85f8c0c23af4bcf33558c57472fcf9d913e8
