TRD: merging TracketCheck and TrackletCountCheck

[deependra170598]

Hi @martenole !
In this PR , I tried to merge two checks: TrackletCheck and TrackletCountCheck.
Please check if everything seems fine. If everything is fine I will remove commented statements.

One issue I see is that check class can read default parameters written in code
for example:
mStatThresholdPerTrigger = std::stof(mCustomParameters.atOrDefaultValue("StatThresholdPerTrigger", "1000.0", *mActivity));

but can not read default parameter provided with config
for example:

[martenole]

I stumbled upon this as well and don't really like the framework API. Basically you should not use the atOrDefaultValue method, as this will give you always the default value from the code and not from the json unless you have provided a value for the explicit activity type and beamType. Took me also a bit to figure out what to use. Please change all these to use atOptional like below:

Suggested change

	mThresholdMeanHighPerTimeFrame = std::stof(mCustomParameters.atOrDefaultValue("UpperthresholdPerTimeFrame", "600000.0" /*default value*/, *mActivity));
	mThresholdMeanHighPerTimeFrame = std::stof(mCustomParameters.atOptional("UpperthresholdPerTimeFrame", *mActivity).value_or("6e5"));

I also think that with the scientific notation long numbers are more easy to read..

[martenole]

Did not go through everything in detail, but looks good to me