more efficient node.js process startup (#7661)
### Description
* Slow start for the concurrency of parallel booting node.js processes
(1, 2, 4, ...)
* Depending on historic statistics avoid booting up a new process, but
wait for one to finish computing
Loading the `/home` route on 16-core machine
Before:
```
16 x Node.js process startup 9.09s avg 568.07ms
16 x Node.js initialization 10.58s avg 660.96ms
276 x Node.js evaluation 30.17s avg 109.30ms
```
After:
```
7 x Node.js process startup 1261.79ms avg 180.26ms
7 x Node.js initialization 3.15s avg 450.21ms
276 x Node.js evaluation 29.41s avg 106.55ms
```
### Testing Instructions
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Give a quick description of steps to test your changes.
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Closes PACK-2680
