Revert IMU angular velocity bug mitigation (FIRST-Tech-Challenge#173)

* fix: corrected the angular velocity axes

See SDK issue FIRST-Tech-Challenge#251

* Update TeamCode/src/main/java/org/firstinspires/ftc/teamcode/drive/SampleMecanumDrive.java

- better description

Co-authored-by: Ryan Brott <rcbrott@gmail.com>

* fix: changed tank class comment to match mecanum

* fix: remove ang velo bug note

- Fixed in SDK 8.0

Co-authored-by: Ryan Brott <rcbrott@gmail.com>

TeamCode/src/main/java/org/firstinspires/ftc/teamcode/drive/SampleMecanumDrive.java

@@ -298,12 +298,7 @@ public double getRawExternalHeading() {
 
     @Override
     public Double getExternalHeadingVelocity() {
-        // To work around an SDK bug, use -zRotationRate in place of xRotationRate
-        // and -xRotationRate in place of zRotationRate (yRotationRate behaves as 
-        // expected). This bug does NOT affect orientation. 
-        //
-        // See https://github.com/FIRST-Tech-Challenge/FtcRobotController/issues/251 for details.
-        return (double) -imu.getAngularVelocity().xRotationRate;
+        return (double) imu.getAngularVelocity().zRotationRate;
     }
 
     public static TrajectoryVelocityConstraint getVelocityConstraint(double maxVel, double maxAngularVel, double trackWidth) {

TeamCode/src/main/java/org/firstinspires/ftc/teamcode/drive/SampleTankDrive.java

@@ -302,12 +302,7 @@ public double getRawExternalHeading() {
 
     @Override
     public Double getExternalHeadingVelocity() {
-        // To work around an SDK bug, use -zRotationRate in place of xRotationRate
-        // and -xRotationRate in place of zRotationRate (yRotationRate behaves as
-        // expected). This bug does NOT affect orientation.
-        //
-        // See https://github.com/FIRST-Tech-Challenge/FtcRobotController/issues/251 for details.
-        return (double) -imu.getAngularVelocity().xRotationRate;
+        return (double) imu.getAngularVelocity().zRotationRate;
     }
 
     public static TrajectoryVelocityConstraint getVelocityConstraint(double maxVel, double maxAngularVel, double trackWidth) {