variable $maxParallelRequests should be configurable per config.ini of the module

[carraroj]

The vspheredb-daemon fails after too much requests in the pipeline but only 30 requests can be handle parallel.
In big environments with many Vcenters and ESXi hosts is this a problem.

Solution is, to set a higher value in the variable $maxParallelRequests of the file
.../vendor/gipfl/curl/src/CurlAsync.php in the module.

The best way is to make this configurable in config.ini of the module to ensure update compatible.

[carraroj]

ref/NC/811688