Prebid Core : fix issue of mergeConfig

[pm-azhar-mulla]

Type of change

• Bugfix

Description of change

We have observed following behaviour during our testing.
When mergeConfig is used after setConfig, all the properties which have object as value in the config are merged or get the latest value but the properties which are non-object, are not merged or does not get the latest value.
e.g:

pbjs.setConfig({
  testProp: 2000,
  testObj: {
     a1: 1
  }
});

pbjs.mergeConfig({
  testProp: 3000,
  testObj: {
     a1: 2,
     a2: 3
  }
});

After the above statements execution, the value of config object becomes

testProp: 2000,
testObj: {
  a1: 2,
  a2: 3
}

Here the value of testObj is merged but testProp isn't.
The reason being, when we call mergeConfig, it calls mergeDeep internally on the conflicting properties.
Since mergeDeep only works for object, we get above behaviour.

Solution:
Instead of using a mergeDeep on conflicting properties, we have used it on complete object.

[patmmccann]

@pm-azhar-mulla @pm-harshad-mane @mike-chowla we have witnessed many properties dropping from the pubmatic endpoint call in prebid 7.8 with the jw boost rtd adapter installed. Is this the fix?