Various fixes (opa property, creation of deploy and besteffort, cosmetic stuff)

Several commits to fix various issues in the OAR properties generator:

• bug 11245 https://intranet.grid5000.fr/bugzilla/show_bug.cgi?id=11245
• bug 11352 https://intranet.grid5000.fr/bugzilla/show_bug.cgi?id=11352
• bug 10705 https://intranet.grid5000.fr/bugzilla/show_bug.cgi?id=10705