[Metrics API] Rename init to build (open-telemetry#2232)

Author: utpilla

metrics_counter.rs

@@ -31,7 +31,7 @@ lazy_static! {
         "value1", "value2", "value3", "value4", "value5", "value6", "value7", "value8", "value9",
         "value10"
     ];
-    static ref COUNTER: Counter<u64> = PROVIDER.meter("test").u64_counter("hello").init();
+    static ref COUNTER: Counter<u64> = PROVIDER.meter("test").u64_counter("hello").build();
 }
 
 thread_local! {

metrics_gauge.rs

@@ -28,7 +28,7 @@ lazy_static! {
         "value1", "value2", "value3", "value4", "value5", "value6", "value7", "value8", "value9",
         "value10"
     ];
-    static ref GAUGE: Gauge<u64> = PROVIDER.meter("test").u64_gauge("test_gauge").init();
+    static ref GAUGE: Gauge<u64> = PROVIDER.meter("test").u64_gauge("test_gauge").build();
 }
 
 thread_local! {

metrics_histogram.rs

@@ -31,7 +31,7 @@ lazy_static! {
         "value1", "value2", "value3", "value4", "value5", "value6", "value7", "value8", "value9",
         "value10"
     ];
-    static ref HISTOGRAM: Histogram<u64> = PROVIDER.meter("test").u64_histogram("hello").init();
+    static ref HISTOGRAM: Histogram<u64> = PROVIDER.meter("test").u64_histogram("hello").build();
 }
 
 thread_local! {

metrics_overflow.rs

@@ -24,7 +24,7 @@ lazy_static! {
     static ref PROVIDER: SdkMeterProvider = SdkMeterProvider::builder()
         .with_reader(ManualReader::builder().build())
         .build();
-    static ref COUNTER: Counter<u64> = PROVIDER.meter("test").u64_counter("hello").init();
+    static ref COUNTER: Counter<u64> = PROVIDER.meter("test").u64_counter("hello").build();
 }
 
 thread_local! {