backport to rel/7.0: missing mpu bucket prefix [S3C-632]

[electrachong]

(cherry picked from commit 2fb0b68)

I think we should backport this fix to rel/7.0 since the release was affected by this bug as well.

[electrachong]

@ironman-machine

[ironman-machine]

Hello @electrachong

Starting end to end procedure using the following payload:
{"REPO_NAME": "S3", "DEFAULT_BRANCH": "rel/7.0", "SCALITY_S3_BRANCH": "backport/fix-mpu-prefix"}

Please follow http://ci.ironmann.io/gh/scality/Integration/13967 for CI status.

[electrachong]

end-to-end passed (I think regular ci tests are failing because they are not run with rel/7.0 arsenal branch)

[rahulreddy]

Wasn't the bug introduced when the routes were extracted in Arsenal which was after the 7.0 release? If yes, why do we need this to be backported?

[electrachong]

I think it was merged before the 7.0 release / branch was created:
https://github.com/scality/S3/commits/rel/7.0

[electrachong]

@ironman-machine after locking dependency packages

[ironman-machine]

Hello @electrachong

Starting end to end procedure using the following payload:
{"REPO_NAME": "S3", "DEFAULT_BRANCH": "rel/7.0", "SCALITY_S3_BRANCH": "backport/fix-mpu-prefix"}

Please follow http://ci.ironmann.io/gh/scality/Integration/13980 for CI status.

[electrachong]

end to end passed, altho regular ci is still failing (I guess this time because of cache..)