Migrate AWS SDK to v2

[vpnachev]

How to categorize this PR?
/area security ipcei
/kind enhancement
/label ipcei/workload-identity

What this PR does / why we need it:
Migrate AWS SDK to v2

Which issue(s) this PR fixes:
Fixes #838

Special notes for your reviewer:
Part of gardener/gardener#9586
Release note:

AWS SDK has been upgraded to v2.

[gardener-robot]

@vpnachev Label ipcei/workload-identity does not exist.

[gardener-robot]

@vpnachev Label ipcei/workload-identity does not exist.

[ishan16696]

/assign

[ishan16696]

few nits:

[ishan16696]

I have performed these tests with/without object lock enabled S3 bucket. Everything works fine

Restoration tests:

• Restoration functionality of backup-restore should work with buckets which don't have bucket/object lock enabled (Backward compatibility).
• Restoration functionality of backup-restore should work with buckets which have both versioned immutable as well as mutable, non-versioned snapshots present.
• Restoration functionality of backup-restore should work with buckets which have only immutable versioned snapshots(full as well as delta) present.
• Restoration functionality of backup-restore should work when attacker corrupted/deleted immutable versioned snapshots present in bucket.

To ignore the snapshots:

• support of skipping/ignoring of any snapshot in an object lock enabled S3 bucket.

For Garbage collection of snapshots:

• Backward compatibility with buckets which don't have immutability enabled.
• GC should work with buckets which have both immutable as well as non immutable objects.
• GC should work with buckets which have only immutable objects.

[ishan16696]

I have tested the copy-backup tasks as well, basically coping the snapshots from source bucket(with object locked enabled ) to target bucket.

[ishan16696]

LGTM!!