Business Dashboard UI: invalid COA tooltip when Address Change is pending and in the past

**Describe the bug in current situation**
In a particular error case, the Office Addresses tooltip displays "null" instead of the effective date.

The error case is that the COA was submitted but is still filed and pending after its expected date. In the following example, the COA should have been effective on Sep 10, 2025, but here we are on Sep 17 and it's still pending.

The code that determines the effective date returns nothing if the date is no longer in the future, as in this case.

**Link bug to the User Story**
N/A

**Impact of this bug**
The tooltip is wrong and not helpful.

**Chance of Occurring (high/medium/low/very low)**
Low, as this requires the Filer to fail to process the COA filing.

**Pre Conditions: which Env, any pre-requesites or assumptions to execute steps?**
N/A

**Steps to Reproduce**
See https://business-dashboard.bcregistry.gov.bc.ca/BC1555158.

**Actual/ observed behavior/ results**
The tooltip is invalid.

**Expected behavior**
Something better -- need to ask UX team about this.

**Screenshots/ Visual Reference/ Source**
See above.