component/tesseract: fix permissions of downloaded traineddata

With the default umask of running slapos node, the default umask create files
that are only readable by user, not by group:

    slapuser10@COMP-1234:~$ ls -al /opt/slapgrid/bf0ccebdbd76d491bcbe16b7998529b2/parts/tesseract/share/tessdata/
    total 125296
    drwxr-x--- 4 slapsoft slapsoft 4096 Jul 13 05:57 .
    drwxr-x--- 3 slapsoft slapsoft 4096 Jul 13 05:57 ..
    -rw------- 1 slapsoft slapsoft 44366093 Jul 13 05:57 chi_sim.traineddata
    drwxr-x--- 2 slapsoft slapsoft 4096 Jul 13 05:57 configs
    -rw------- 1 slapsoft slapsoft 23466654 Jul 13 05:57 eng.traineddata
    -rw------- 1 slapsoft slapsoft 14213351 Jul 13 05:57 fra.traineddata
    -rw------- 1 slapsoft slapsoft 35659159 Jul 13 05:57 jpn.traineddata
    -rw------- 1 slapsoft slapsoft 10562874 Jul 13 05:57 osd.traineddata
    -rw-r--r-- 1 slapsoft slapsoft 572 Jul 13 05:57 pdf.ttf
    drwxr-x--- 2 slapsoft slapsoft 4096 Jul 13 05:57 tessconfigs

but when using multiple users, partitions users are members of slapsoft group,
so these files needs to be group readable.