[content-service] Fix backup restore

[aledbf]

Description

Partial revert of #9589. Only reverts the restore part.

How to test

• Open a workspace. In the terminal execute:

touch basic
sudo touch root-file
touch executable-file
chmod +x executable-file
touch suid-file
chmod 2555 suid-file
mkdir suid-directory
chmod g+s suid-directory

• Check the output of ls -lat, should be similar to

drwxr-x--- 8 gitpod gitpod 4096 Apr 28 17:31 .
-r-xr-sr-x 1 gitpod gitpod    0 Apr 28 17:31 suid-file
drwxr-sr-x 2 gitpod gitpod    6 Apr 28 17:31 suid-directory
-rwxr-xr-x 1 gitpod gitpod    0 Apr 28 17:30 executable-file
-rw-r--r-- 1 root   root      0 Apr 28 17:30 root-file
-rw-r--r-- 1 gitpod gitpod    0 Apr 28 17:30 basic

• Stop and open the workspace
• Open a terminal and run ls -lat
• Compare the outputs

Release Notes

[content-service] Fix backup restoration

xref #9730

[kylos101]

Works as advertised, plus, will unblock gitpod-staging.com.

CC: @geropl @jankeromnes

[mustard-mh]

Tested, now it works

[geropl]

Testing...

[geropl]

Works, awesome!

[akosyakov]

LGTM