Add a benchmark script for Hlt2 rate test

Add a benchmark script Moore_hlt2_rate_and_size.sh to run Hlt2 rate and event size test.

Currently the test has the same setup as Moore_spruce_rate_and_size

It will produce one log file and one monitoring file, which can be processed by the RateTestHandler in LHCbPR2HD. The handler will produce:

• A pie chart of lines per WG:

• A stacked histogram of rates:

• Two stacked histograms of event sizes, one for DstData Rawbank and the other for total event size:

• Several webpages listing the rates/event sizes, take the one for rates as an example here: all_rates.html

Several pending items:

• Decide the number of event to process, also change the Sprucing one if needed: set both to 1e5
• Add the test in LHCbNightlyConf: will do this later, add it together with the Sprucing throughput test

Requires lhcb/Moore!1632 (merged).