fix: symbols pagination #506

[habibalkhabbaz]

Description

Let's say we are monitoring 5 symbols and we add one more symbol to our Global Settings.
The bot will cache it to trailing-trade-cache collection in our Mongo DB as usual and this symbol will show up in the frontend as expected.

• Symbols in Global Settings: 6
• Symbols cached in DB: 6

However, when we remove that symbol from the Global Settings, the symbols count will be different than the cached symbols in our database.

• Symbols in Global Settings: 5
• Symbols cached in DB: 6

This is still expected but the pagination will have an issue when we reached like:

• Symbols in Global Settings: 12
• Symbols cached in DB: 13

Hence, we can see only the first 12 symbols from the frontend and we will not be able to see the symbol number 13 because we were paginating our symbols based on the count of symbols that exists in Global Settings.

The correct behavior is to count the symbols from the trailing-trade-cache collection which is addressed by this PR.

I also added an explanation for that when the count becomes different just to be clear.

Related Issue

#506

Motivation and Context

How Has This Been Tested?

Tests provided

Screenshots (if appropriate):

[chrisleekr]

Hi @habibalkhabbaz

As always, your contribution is very good and clean.

I merge in.