Minor System::Clock cleanup

[kpschoedel]

Problem

Followups from PR #10056 Indirect access for System::Clock functions

Fixes #10146 Remove GetMonotonicMicroseconds() call
Fixes #10145 remove.
Fixes #10144 The static cast should have the / 1000 within it

Change overview

• Removes the global backward-compatibility wrappers for GetMonotonic…().
• Correctly parenthesize the Remove GetMonotonicMicroseconds() call #10146 cast.

Testing

CI. No changes to functionality intended.

[github-actions]

Size increase report for "gn_qpg-example-build" from 80df9f2

File	Section	File	VM
chip-qpg6100-lighting-example.out	.text	16	16

Full report output

BLOAT REPORT

Files found only in the build output:
    report.csv

Comparing ./master_artifact/chip-qpg6100-lighting-example.out.map and ./pull_artifact/chip-qpg6100-lighting-example.out.map:

BLOAT EXECUTION FAILED WITH CODE 1:
bloaty: unknown file type for file './pull_artifact/chip-qpg6100-lighting-example.out.map'

Comparing ./master_artifact/chip-qpg6100-lighting-example.out and ./pull_artifact/chip-qpg6100-lighting-example.out:

sections,vmsize,filesize
.debug_loc,0,45
.debug_info,0,19
.text,16,16
.debug_abbrev,0,14
.debug_line,0,6
.debug_frame,0,4
[Unmapped],0,-16

[github-actions]

Size increase report for "nrfconnect-example-build" from 80df9f2

File	Section	File	VM
chip-shell.elf	text	16	16
chip-lock.elf	text	16	16

Full report output

BLOAT REPORT

Files found only in the build output:
    report.csv

Comparing ./master_artifact/chip-shell.elf and ./pull_artifact/chip-shell.elf:

sections,vmsize,filesize
.debug_info,0,19
.debug_loc,0,16
text,16,16
.debug_abbrev,0,14
.debug_frame,0,4
.debug_line,0,3

Comparing ./master_artifact/chip-lock.elf and ./pull_artifact/chip-lock.elf:

sections,vmsize,filesize
.debug_loc,0,36
.debug_info,0,19
text,16,16
.debug_abbrev,0,14
.debug_line,0,7
.debug_frame,0,4

[github-actions]

Size increase report for "esp32-example-build" from 80df9f2

File	Section	File	VM
chip-all-clusters-app.elf	.flash.text	24	24

Full report output

BLOAT REPORT

Files found only in the build output:
    report.csv

Comparing ./master_artifact/chip-all-clusters-app.elf and ./pull_artifact/chip-all-clusters-app.elf:

sections,vmsize,filesize
.debug_loc,0,128
.flash.text,24,24
.debug_line,0,16
.debug_frame,0,4
[Unmapped],0,-24

[andy31415]

@project-chip/reviewers-apple ? @Damian-Nordic @jepenven-silabs @jmartinez-silabs @hawk248 @jelderton @LuDuda @chrisdecenzo ?