CRM-21677 reduce unnecessary joins in mailing reports

[yashodha]

Overview

Partial of #11814 which is a reviewers cut of #11550
Reduce unnecessary joins in mailing reports :

Mailing/Bounce
Mailing/Clicks
Mailing/Detail
Mailing/Opened

Before

unnecessary joins to phone table in mailing reports

After

join only when needed, code standardised

Comments

@eileenmcnaughton : want to merge this?

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• CRM-21677: Report improvements

[eileenmcnaughton]

I tested these 4 reports & noted a) that the report ran with & without the phone field present & b) that the phone table was / wasn't present in the query accordingly.

I note the email table / field could do with the same treatment on these reports & these class vars could be removed:

  protected $_emailField = FALSE;

  protected $_phoneField = FALSE;

but that should not delay the merge - merging