fix: improve uptime status sed script to report correct units for a few uptime scenarios

[xafarr]

10:31 up 36 mins, 2 users, load averages: 2.55 4.87 6.81

9:42 up 10 days, 25 mins, 2 users, load averages: 4.71 4.27 4.00

18:43 up 21 days, 9 hrs, 2 users, load averages: 3.99 6.48 10.99

The following are examples of current and fixed sed scripts.

Uptime String: 18:43  up 9 hrs, 2 users, load averages: 3.99 6.48 10.99
Current SED: 9 hrsm
Fixed SED: 9h

Uptime String: 18:44  up  9:01, 2 users, load averages: 4.94 6.21 10.55
Current SED: 9h 01m
Fixed SED: 9h 01m

Uptime String: 9:31  up 45 secs, 2 users, load averages: 105.51 24.01 8.61
Current SED: 45 secsm
Fixed SED: 45s

Uptime String: 9:32  up 2 mins, 2 users, load averages: 109.13 55.55 22.93
Current SED: 2sm
Fixed SED: 2m

Uptime String: 22:37:29 up 4 days,  9:44,  1 user,  load average: 0.07, 0.03, 0.01
Current SED: 4d 9h 44m
Fixed SED: 4d 9h 44m

Uptime String: 11:24  up  1:54, 2 users, load averages: 5.25 11.69 13.95
Current SED: 1h 54m
Fixed SED: 1h 54m

Uptime String: 9:30  up 3 days, 0 sec, 2 users, load averages: 3.83 4.47 4.04
Current SED: 3d 0 secm
Fixed SED: 3d 0s

Uptime String: 9:42  up 3 days, 12 mins, 2 users, load averages: 4.71 4.27 4.00
Current SED: 3d 12sm
Fixed SED: 3d 12m

Uptime String: 9:56  up 10 days, 26 mins, 2 users, load averages: 2.26 2.28 2.49
Current SED: 10d 26sm
Fixed SED: 10d 26m