HTTP-triggered Function can be triggered despite being disabled

_Derived from Stackoverflow [question](https://stackoverflow.com/questions/57351710/disable-attribute-nor-application-settings-on-httptrigger-azure-function-not-wor)._

According to [this ](https://docs.microsoft.com/en-us/azure/azure-functions/disable-function#functions-2x---all-languages)article I disabled a HTTP-triggered function using an app setting

"AzureWebJobs.Http2BlobFunction.Disabled": "true"

Starting up the function, it also shows up in the console output of the function runtime

Function Http2BlobFunction is disabled

However, you can still call the function on its API and it gets executed alright.
Looks like a bug to me.

#### Investigative information

Please provide the following:

Azure Functions Core Tools (2.7.1505 Commit hash: eb8182995562240ca83dd0e0e3394586cf5fdfa3)
Function Runtime Version: 2.0.12590.0

#### Repro steps

See above. Create an HTTP triggered function and disable it using an app setting.

#### Expected behavior

Function should not be executed when called. Return a 404 or something like this.

#### Actual behavior

Function does get executed.


(The other two functions are not disabled, so that's ok. But Http2BlobFunction is disabled)

#### Known workarounds

None

#### Related information

Only tested in C# so far.