BUG/MINOR: mworker/cli: fix show proc pagination using reload counter

BUG/MINOR: mworker/cli: fix show proc pagination using reload counter

After commit 594408cd612b5 ("BUG/MINOR: mworker/cli: 'show proc' is limited
by buffer size"), related to ticket #3204, the "show proc" logic
has been fixed to be able to print more than 202 processes. However, this
fix can lead to the omission of entries in case they have the same
timestamp.

To fix this, we use the unique reload counter instead of the timestamp.
On partial flush, set ctx->next_reload = child->reloads.
On resume skip entries with child->reloads >= ctx->next_reload.
Finally, we clear ctx->next_reload at the end of a complete dump so
subsequent show proc starts from the top.

Could be backported in all stable branches.