Change "elderly" to "older adults" #2230

Describe the bug
Reported issues with the word "Elderly" in the census demographic data. Change to "Older adults".

To Reproduce
Steps to reproduce the behavior:

1. Go to 'explore the map / any census tract'
2. Click on 'age'
3. See error

Expected behavior
Update string.

Screenshots
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Desktop (please complete the following information):

• OS: [e.g. iOS]
• Browser [e.g. chrome, safari]
• Version [e.g. 22]

Smartphone (please complete the following information):

• Device: [e.g. iPhone6]
• OS: [e.g. iOS8.1]
• Browser [e.g. stock browser, safari]
• Version [e.g. 22]

Additional context
Add any other context about the problem here.