[UI] Whirlpool loading bars indentation with different mix counts

[RequestPrivacy]

Description

The loading bars could be indented more consistently if there are UTXOs with different mixing counts (e.g. with utxos with one digit and two digit mixing history like 9 and 10 the loading bar seems to be intended by one digit?!), also see the "number 1"-labeling in the screenshot provided in #597.

Mixes
 --------loading bar--------    9
--------loading bar--------    10

Maybe it is possible to have them exactly below each other even if the digit count of the numbers are different or else maybe change to a numbering system with a fixed amount of digits like maybe 4:

Mixes
--------loading bar--------    0004
--------loading bar--------    0200
--------loading bar--------    0010
--------loading bar--------    4000