ACU Omnibus, July 2023 (#480)

* ACUAgent: never upload fewer than 4 points on start of leg

Otherwise, a scan that is aborted after only a couple of points on the
next leg have been uploaded will lead to a ProgramTrack error (and Az
summary fault).

* ACUAgent: fix 2 small bugs in exercise mode

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* ACU: work-around for OCSClient when OCS_CONFIG_DIR not set

This is needed on site system, as --site-file is used and
OCS_CONFIG_DIR is not set.

* ACU: bugfix last commit

* ACU: reduce data rate from "monitor" process

Fields are updated at most once every 2 seconds unless the values have
changed; an exception is the "summary" group, which is uploaded on
every query to provide a basic timeline for when all fields were
queried.

* ACU: reduce influx post rate from "monitor" process

Fields are updated at most once every 2 seconds, unless values have
changed.

* ACU: defaults for az_speed, az_accel in generate_scan

Coming soon, these can be changed through a task ...

* ACU: report DefaultScanParams in monitor session.data

* ACU: new set_scan_params task to update (or reset) defaults

* ACU: make el_endpoint args optional

* ACU: _go_to_axes handler; generate_scan will seek to init el

* ACU: fix linter complaints

* ACU: improve docstrings for recent edits

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Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>