Use appropriate buffer for QgsGeometry::XXXContainedInLine. Fix #10999.

We have reduced the problem by reducing the size of the buffer used in QgsGeometry::XXXContainedInLine functions.
The error may still occur depending on:
   the accuracy of the projection used,
   the distance between the object to modify and the nearest point.
So we caught the error, stop capturing and displaying a more specific message.
ouch.  pow(1.0L, ...) should be pow(10.0L, ...).    The idea was to use 4 of the 15 significant decimal digits of a double as buffer.

1000000 => 0.00001
180 => 0.000000001