Reverse ordering of dcdb.sensordata table for better ScyllaDB performance and reverse it again in libdcdb to retain the original ordering

Revert "Whitelist only the specified Cassandra server for connections" to support the Murmur3 Partitioner used in ScyllaDB

This reverts commit d153944d.

- We now use parallel asynchronous queries on multiple sensors

Move io_context creation out of AnalyticsController into main() and pass it to PluginManager and OperatorManager constructors instead of initPlugin() and startPlugin(). This avoids passing it to RestAPI.

Make parameters to SensorDataStore functions const where possible. Requires recompiling of binaries that depend on libdcdb!

- Allows to set a variety of conditions on sensor data and raise
alarms when they are triggered
- Arbitrary scripts can be executed (e.g., to send emails) when
alarms happen

- Also added support for multiple accept sockets when a single hostname
maps to multiple IPs

- Now using the global thread pool in dcdbpusher, collectagent and
grafanaserver to boost performance

- Fixing warnings here and there

- Plus other logging consistency changes