I'm using the Bluepill STM32F103C8T6.
Is it possible to configure the GPIO in such a way that the I2C can be enabled on other pins than:
No it is not possible to do hardware I2C on other ports than the ones you named on the STM32F103C8T6. The hardware is only routed to those GPIO ports.
You can write a software I2C driver which can be used on any open-collector or open-drain GPIO pin. Best thing to do for that is to look at the Arduino software I2C implementation.