Don't depend on String8 cast to C string [health]

Bug: 295394788
Test: m checkbuild
Change-Id: I67f0468dc21dfb0baab58361078f4f7bc750bdbd
diff --git a/health/1.0/default/convert.cpp b/health/1.0/default/convert.cpp
index 31b4679..e12e197 100644
--- a/health/1.0/default/convert.cpp
+++ b/health/1.0/default/convert.cpp
@@ -117,7 +117,7 @@
     info.batteryCycleCount      = p->batteryCycleCount;
     info.batteryFullCharge      = p->batteryFullCharge;
     info.batteryChargeCounter   = p->batteryChargeCounter;
-    info.batteryTechnology      = p->batteryTechnology;
+    info.batteryTechnology      = p->batteryTechnology.c_str();
 }
 
 void convertFromHealthInfo(const HealthInfo& info,