Use saved contribution's line items rather than the primaryContributionID

[eileenmcnaughton]

Overview

Simplifies the completeOrder function by not using 2 methods to calculate which contribution to get the membership number of terms from

Before

$lineItems either already exists or were created in repeattrransaction and have the num_terms parameter. However, we ignore & calculate num_terms separately

After

We no longer use 2 calculations

Technical Details

By the time we reach this point in the code we know that

1. the contributon exists and it has an id
2. it has line items - either those created in it's pending stage or those calculated in repeattransaction

Therefore we can reasonably assume these line items are accurate now and use them, rather than the confusing
primaryContributionID that we have doubts about the validity of

Comments

@mattwire - I need to check that there is relevant & specific test cover - but I think removing the second usage of primaryContributionID might actually be this simple

[civibot]

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[eileenmcnaughton]

So this passed - I found that on the completetransaction side it is clearly tested (I added a comment to the relevant test)

[eileenmcnaughton]

There was no test cover on this for repeattransaction - I added

[eileenmcnaughton]

test this please

[eileenmcnaughton]

This is passing now