* Remove `estimatedGas` property from `txMeta`
The `estimatedGas` property was a cache of the gas value estimated for
a transaction when the default gas limit was set. This property wasn't
used anywhere. It may have been useful for debugging purposes, but the
same gas estimate is already stored on the `history` property so it
should be present in state logs regardless.
* Remove `gasLimitSpecified` txMeta property
The `gasLimitSpecified` property of `txMeta` wasn't used for anything.
It might have been useful for debugging purposes, but whether or not
the gas limit was specified can also be determined from looking at the
transaction history, so it's not a huge loss.
* Remove `gasPriceSpecified` txMeta property
The `gasPriceSpecified` property of `txMeta` wasn't used for anything.
It might have been useful for debugging purposes, but whether or not
the gas price was specified can also be determined from looking at the
transaction history, so it's not a huge loss.
* Remove `simpleSend` txMeta property
The `simpleSend` property of `txMeta` was used to ensure a buffer was
not added to the gas limit during gas estimation for simple send
transactions. It was made redundant by #8484, which accomplishes this
without the use of this property.
This state has been removed from the background. It was used for the
old UI, and has been unused for some time. A migration has been added
to delete this state as well.
The action creator responsible for updating this state has been removed
from the UI as well, along with the `callBackgroundThenUpdateNoSpinner`
convenience function, which was only used for this action.
